Franz von Werra, a flying ace of the Luftwaffe, is the only German known to have escaped Allied captivity and to have definitely made it back to Germany during the Second World War. His journey began in England in September 1940, when he was shot down near Kent and interrogated at length in camps in London and Middlesex. Then, he was taken to a holding camp in Cumbria, from which he briefly escaped while out on a walk. He was captured five days later and taken to a second camp in Derbyshire, from which he escaped through a tunnel he helped to dig. Once out of the camp and in the village of Swanwick, he convinced a number of locals that he was a Dutch pilot serving with the Royal Air Force, that he had been forced down on his way back from an Allied attack on Denmark and that he needed to reach the nearest RAF aerodrome. He was assisted in making his way to an aerodrome in Nottingham, where he maintained his story and was almost ready to fly away. He was arrested as he sat in the cockpit of a Hurricane, about to take off. Days later, in January 1941, von Werra was dispatched to Canada with over a thousand other prisoners. Most Axis personnel captured in or around Britain were sent to the dominions in the first half of the war to avoid maintaining an army of enemy soldiers in the country, ready to be liberated in the event of an invasion. No sooner had he reached Canada, von Werra did what came most naturally to him by that point: he jumped from the moving train taking him to his new camp. Knee-deep in snow, he made his way to the St. Lawrence riverbank and crossed over to New York on a rowing boat. From the then neutral United States, he made his way to Mexico, then Peru, Bolivia, Brazil, Spain and Italy, eventually making it to Berlin in April, where he received the Knight’s Cross of the Iron Cross from Hitler’s own hands.¹

Already extraordinary, von Werra’s escape was even more significant because of what he had experienced while in Britain. Unlike most prisoners, von Werra had gone through the entire system of interrogation set up to elicit tactical, operational and strategic information from the enemy. Fewer than 1 per cent of all Germans captured by Britain during this conflict would share von Werra’s interrogation experience. His return home thus caused a panic in Britain. But it also created concern in Germany, which had now realised how much information its soldiers were giving away. For this reason, von Werra was asked by Hermann Göring to help train new recruits on how to evade British interrogations as well as to improve the Luftwaffe’s interrogations of Allied airmen, which compared to the British proved to be rudimentary.

How could it be that Germans were divulging intelligence to the British? German soldiers were known for their strong sense of military honour. Many of the interrogation reports produced in the first year of the war prove this point, with prisoners refusing to talk. It was precisely the fact that much information was being obtained without prisoners realising that they were giving it that was discovered through von Werra’s account. Interrogation was designed so as not to rely on prisoners’ willingness to give what they perceived to be ‘intelligence’, but rather to enable the systematic collection of seemingly trivial information, such as when a prisoner had last been on leave. At the individual level, questions about leave seemed harmless and were often answered. At a mass level, such answers would indicate how much strain the Wehrmacht was under and hence how infrequently it was allowing personnel to go on leave, information that was useful to the War Office and included in its weekly intelligence summaries. Other examples are changes to individuals’ salaries or how speedily they were being promoted, information that would contribute to Ministry of Economic Warfare analyses on economic conditions in Germany. In a total war, the collection of information was similarly total.

Sophisticated as it was, the subtle gathering of ‘big data’ was not interrogation’s only function. The camps that von Werra passed through had developed an elaborate process which used several methods to collect the kind of intelligence prisoners were often unwilling to share. Such methods included direct interrogation, stool pigeons and concealed microphones, which were used to monitor conversations between prisoners, between prisoners and stool pigeons, and between prisoners and interrogators. The von Werra scare was therefore not as disruptive as it might have been because the sophistication of the interrogation process in Britain was never realised. It is true that many prisoners suspected that their conversations were being monitored, but this rarely prevented them from talking.² Many of those initially tight-lipped would, after inspecting the room, assure themselves that no devices were present. In other cases, dummy microphones were put in obvious places so that prisoners looking for them could find them – as indeed von Werra did, behind a ventilator grille – and move to have their conversations at the opposite end of the room, where the real microphones were hidden behind walls and ceiling roses. Plastered over, they were undetectable.

The cables from these microphones led to what was colloquially known as the ‘M’ Room, with ‘M’ standing for mother – because ‘Mother’ was always listening.³ There, staff from the Pioneer Corps, most of them Germans or German-speaking refugees and often Jewish, would listen in and produce verbatim excerpts of discussions deemed useful. Each excerpt would then be circulated to multiple government departments and agencies, whose interests this operation was designed to serve. But it was almost as if this operation was designed to excite as well. Its mere existence was full of intrigue: grandiose stately homes with state-of-the-art technology plastered behind the walls, picking up whatever intelligence the men of the Wehrmacht were unknowingly spilling out. Meanwhile, hidden in the basement some of the regime’s victims were transcribing what was being said, then passing it to a network of recipients ready to use those conversations against Nazi Germany.

That Britain was using microphones to eavesdrop on prisoners is now something close to common knowledge for those interested in the Second World War. Yet for all the attention the use of microphones is bound to attract, there is much that is unknown about the process that generated them.⁴ Who decided what conversations to record? Who was monitored, and why? The question of why is far from self-evident when the transcripts are read on their own. Some are a couple of sentences long, they concern topics apparently unrelated between them and the identity of the speakers is unknown, with soldiers’ names replaced by a code. Some contained information that was clearly intelligence, such as descriptions of weapons, but others contained only what was rightly called Nazi claptrap. Take for example a transcript from August 1940 which simply read: ‘I am the ping-pong champion of West Germany. But I am out of practice. I gave up the game after a typical Jew-boy – sixteen years old – had beaten me. Then I said to myself: “That is certainly not real sport!”.’⁵ Why was this antisemitic comment, devoid of military information, of interest to intelligence? If you turned the page to see whether the next transcript held any clues, you would be disappointed – it is an unrelated conversation between two different prisoners. The transcript before it is also unconnected – a five-page discussion between two airmen, unwittingly sharing air intelligence concerning the Battle of Britain. Before that, an airman was complaining about the high taxes his father-in-law was paying the regime. As with these examples, many transcripts are striking when read individually, but when read together they become rather disorientating. This is because intriguing as they may be to us, these conversations were not being recorded for posterity. There was a logic and a process behind those recordings, and these need to be retraced.

3.1 On A Wing and A Prayer

The association between covert listening and interrogation dates back to the start of the war in 1939, and had already been at the centre of discussions about interrogation before that September. Although interrogation had been a far less sophisticated affair in the First World War than it was about to become, it had nevertheless been considered an important source by all three service ministries, creating a conviction that it should be exploited further in a new conflict with Germany. This conviction was strengthened by the fact that in the Great War’s final stages, microphones were used to monitor some prisoner conversations, together with old-fashioned eavesdropping done by prison guards. These ad hoc activities yielded some useful intelligence, to the point that a bugged camp was apparently set up in South London in 1918 to exploit this method more systematically. With its planned opening date being – of all days – 11 November 1918, the day on which the war ended, it was never actually used. But when plans for interrogation were dusted off in 1938 following the Munich Agreement, the War Office picked up exactly where it had left off twenty years earlier, aiming to revive the same type of camp. Several properties were considered by the War Office with the Tower of London confirmed as the best place in April 1939, the plan being that it would become operational the day after war broke out.

Commanding this operation would be then Captain Thomas Kendrick, who had until recently worked for SIS. It was the Gestapo that had ended his fifteen-year-long spy career in the field only months earlier, when they arrested him in Austria on his way to England on a three-week holiday. Since the mid-1920s, Kendrick had been based in Vienna where he ran a network of SIS spies concerned primarily with Soviet espionage. To be able to do that, he was formally attached to Vienna as a ‘Passport Control Officer’, an established diplomatic cover for SIS officers on the Continent. Under that cover, he let his staff focus on issuing passports – including to Austrian Jews trying to escape following the Anschluss – while he focused on running several important agents including in Czechoslovakia, Hungary, Italy and Nazi Germany.⁶ When the Gestapo arrested him in August 1938, they had plenty of evidence to support their claim that Kendrick was a spy. They interrogated him extensively over three days before they released him following the intervention of the British ambassador to Berlin, Sir Nevile Henderson, effectively putting an end to his SIS career.⁷ Despite being uncovered, his high standing within SIS made him a natural option to head this new operation in the Tower, which required the skills and discretion of an SIS officer despite the camp itself having nothing to do with SIS. In addition to the fact that his career was forged in SIS, Kendrick was also known for his management skills and for effectively dividing labour among his team in Vienna. He was, in other words, both a good spy and a good leader.

Delegation of duty was to prove instrumental to interrogation, but initially Kendrick had little to delegate. An entry from Guy Liddell’s diary for 13 September 1939 notes that Kendrick was ‘kicking his heels’ in the Tower and had no prisoners to interrogate.⁸ With him, also kicking their heels, was a small team of two interrogation officers, two shorthand writers and two ‘secret listeners’. To these War Office personnel, the Royal Navy and Air Force soon attached their own officers. The arrangement was that the overall administration of the camp – including custody, transport and the bugging activities – would be the responsibility of the War Office, which also had responsibility for interrogating Army prisoners.⁹ But the Royal Navy and Air Force would be able to have their own interrogators, responsible for interrogating Kriegsmarine and Luftwaffe prisoners respectively. This combined, intra-service arrangement was reflected in the name of the organisation, which came to be known as the ‘Combined Services Detailed Interrogation Centre’ (CSDIC, pronounced sizdic).¹⁰ The formal name of this organisation was CSDIC(UK), but here it will be referred to as CSDIC for simplicity. The task of liaising between the camp and the three ministries was given to then Captain Arthur Richard Rawlinson. A successful screenwriter in peacetime, in the previous war Rawlinson had been an intelligence officer with MI1(a), the branch dealing with interrogation at that time.¹¹ On the reserve list since 1919, he had returned to active service earlier in 1939. In January 1940, he became the link between CSDIC and the rest of the intelligence machine, even though initially he split his duties between that and travelling to Walton-on-Thames, where he was helping to produce a propaganda film for British soldiers to show the ‘deplorable results that may follow’ if they said anything more than their rank, name and number in interrogation.¹²

Yet the idea that microphones would simply provide raw intelligence proved to be more complex in practice. While most prisoners captured around the UK were taken to CSDIC between September and December 1939 – a total of 169 men, most of them captured at sea – obtaining useful information from them was a challenge. The first problem was that the technology the War Office possessed was subpar, and the conditions in the medieval Tower were ‘about as unfavourable as can be imagined’ for recording sound.¹³ The second transcript ever to have been produced contained a note, ‘outside interference very noticeable’, which contributed to unintelligible conversations.¹⁴ A further problem was that the methods used to make prisoners open up were too simplistic, and, even worse, detectable by the prisoners, such as British officers posing as Germans to try to gain their trust. On top of this, while the initial policy was that all prisoners would be sent to the Tower for up to three days before being released to permanent camps, some of those released had to be taken back to the Tower when it was realised that more information was needed from them. A bugged conversation between two Luftwaffe prisoners on Christmas Eve 1939 is telling of this problematic process:

• I have already been in the Camp and have been fetched back again … I have had unpleasant experiences here. Even though the treatment is not too bad, I don’t trust these fellows any more. I don’t trust the quietness of it here … They use all sorts of means here to get information out of us. I think it is despicable when they put English officers into German Air Force uniforms.

• They do that?

• Yes, in the Tower … I am very sceptical about our being brought to gather just on Christmas Eve, for we are not generally so well treated. I don’t trust these people. They are doing it for some special reason.¹⁵

Weeks into the war, interrogation was proving a failure. The lack of support from outside CSDIC only exacerbated matters. In the Great War interrogation had been part of MI1, so the same arrangement was resurrected in 1939 without much question. But MI1 was the secretariat of the Directorate of Military Intelligence, responsible for the organisation of intelligence generally rather than a section with any expertise on the collection of human intelligence.¹⁶ Without expertise to advise or support CSDIC, MI1 also lacked the resources necessary to make CSDIC efficient. A prime example was coordination between CSDIC and other departments. While various departments needed prisoners of war to be asked certain questions, MI1 did not have the time to facilitate the necessary communication between them and the camp, leaving interrogators in the dark as to what intelligence they needed to obtain.

Camp staff were anxious to make the process work. A month from CSDIC receiving its first group of prisoners – all forty-three of them crew of a U-boat – a determined Kendrick drove to a stately home in Cockfosters to inspect whether that would make a more suitable camp than the Tower which, for all its symbolism, could not credibly function as an interrogation site.¹⁷ He took with him the regional director of the Radio Corporation of America (RCA) – the leading manufacturer of recording equipment and founder of NBC, the American television and radio network. The company had recently produced state-of-the-art recording equipment intended for musicians – allowing for ‘direct listening, recording, re-recording, monitoring during re-recording and play-back’ – which was much more suitable than the equipment in the Tower.¹⁸ With them was also RCA’s chief engineer.¹⁹ They all concluded that Trent Park, as the estate was called, was indeed more suitable than the Tower, pending alterations. Besides the optimal architectural factors was the fact that it had twelve rooms suitable for bugging, ten more than the Tower. That Trent Park was a country house, until recently frequented by people including Edward VIII, Wallis Simpson, Winston Churchill, Charlie Chaplin and Lawrence of Arabia (all friends of Sir Philip Sassoon, the owner who died just before the war started), was also certain to make prisoners talk to each other more than the Tower of London, with its history of torture and death.²⁰ Things moved quickly from Kendrick’s reconnaissance trip that October and Trent Park started to be used in December.

Favourable developments indirectly affecting CSDIC’s potential were also at play. The realisation that this was going to be a long war meant that the size of the Directorate of Military Intelligence (DMI) had also quadrupled by early 1940, with one of the new sections, MI9, established to assume responsibility for intelligence concerning British prisoners of war, including their interrogation upon repatriation. Once MI9 began operations, it became clear that it would be a more suitable home for CSDIC than MI1. Both MI1 and MI9 thought so and drew up a joint proposal in March 1940, suggesting the transfer so that the interrogations of British and enemy prisoners would complement each other.²¹ The proposal was accepted by the DMI and consequently MI9 was split into two: MI9(a) would deal with enemy prisoner intelligence, including CSDIC, and MI9(b) would deal with intelligence from escaped British prisoners.²² Overlooking both activities was then Major, later Brigadier Norman Crockatt, another veteran of 1914–1918 who ‘in an age of drab clothes and battledress … wore at every opportunity the colourful gear of his regiment, the Royal Scots’.²³ These developments also meant that soon enough, the technology supplied by RCA was replicated and adapted by the government’s Post Office Research Station, so that the entire affair would be completely secret.²⁴

3.2 The System

The developments of early 1940 allowed CSDIC’s staff to begin to master the actual process of interrogation. To them, it was clear that the process so far had been based on a false premise, and that placing anyone and everyone in cells with microphones for up to three days would not, in itself, result in intelligence. At best, it would result in tactics that made prisoners suspicious. Far more beneficial, they thought, would be to send selected prisoners to Trent Park for a longer period, which would give time for CSDIC to liaise with expert departments as to what information they needed, and for prisoners to open up and discuss it. It was only then that microphones would be of use. This was articulated in a meeting with the War Office in February 1940, with staff suggesting that ‘the longer prisoners of war could remain at [Trent Park,] the better it would be’.²⁵ The course of the war in 1940 also made a system of selection necessary for CSDIC; Western Europe had fallen under Nazi rule by the summer, resulting in more prisoners being brought to Britain than before. Not only was it undesirable to continue sending each one of them to CSDIC, it would now also be unfeasible to keep doing so.

Changes outside CSDIC also became entangled with its shifting trajectory at this point. This concerned attempts to have interrogation units in France, with Major Alexander Scotland – another veteran taken out of retirement to join the intelligence effort – sent to Dieppe in March 1940 to lead what was called the Prisoner of War Interrogation Section (PWIS). However, after two months he had to return to England in the most haphazard way. As he himself recalled the events of that fateful May:

Reaching East Sussex the next morning, it seemed that PWIS had reached the end of its own journey as well. Instead of abandoning it, however, the decision was made to turn it into a ‘home’ organisation – the Prisoner of War Interrogation Section (Home), known as PWIS(H). Within a month or so, by July 1940, PWIS(H) would be operating out of nine camps – known as cages – across Britain. The preference was for cages to be in repurposed racecourses, which had plenty of space to accommodate both staff and prisoners. Both Kempton Park Racecourse in Surrey and Doncaster Racecourse became ‘cages’, while in the absence of a racecourse, the Preston North End football stadium became the cage serving Lancashire. The base for PWIS(H), where Scotland himself would also be based, was the London District Cage, situated only a few steps from Kensington Palace and Hyde Park.²⁷ These cages began to act as a ‘sieve’ for CSDIC: they would interrogate all prisoners captured in or brought to the UK in order to select a minority for CSDIC. In the process, the cages would also gather intelligence for General Headquarters, so that CSDIC could focus on long-term intelligence of relevance to the three service ministries more generally. To avoid having either CSDIC or any of the PWIS(H) cages inspected by the International Red Cross or enemy delegations in the event of an invasion, their premises were presented as transit centres rather than as prisoner-of-war camps.²⁸ They were, in other words, completely invisible to most people.

But they were far from invisible to senior figures within British intelligence, the armed forces and the government. The CSDIC premises were constantly being visited by a number of important people, both in order to inspect the work but in some cases also for inspiration: in October 1942 alone, some nine US Army officers visited CSDIC because they were in the process of setting up a similar camp. Many more senior UK officers visited that month alone, including the Director of Military Intelligence, Major-General Davidson (a regular visitor) and the Chief of the Imperial General Staff, Field Marshal Alan Brooke. Other senior figures included the Deputy First Sea Lord, Sir James Grigg who was the Secretary of State for War, as well as Victor Cavendish-Bentinck, Chairman of the Joint Intelligence Sub-Committee and Lord Rothschild visiting on behalf of MI5.²⁹ The London Cage too was regularly visited by many senior ranking officers, both British and American.

This system of interrogation remained in place for the rest of the war, but how busy it was depended on policy towards prisoners in general. As mentioned earlier, while the fear of invasion remained acute, most Germans captured outside the UK were shipped off directly to the dominions rather than brought to Britain. They would have therefore passed through neither PWIS(H) nor CSDIC. Field interrogations became more streamlined after 1940, in order to question these prisoners briefly on matters of immediate relevance to local army headquarters.³⁰ There would even be CSDICs – camps equipped with listening devices – set up in various theatres of war. Those were often mobile units, moving with the war and interested in intelligence relevant to the local general headquarters (e.g. Middle East). Any prisoners thought to have particularly useful information would be dispatched to CSDIC in Britain, but this was rare.

Things changed with the Allied successes in North Africa and Italy as well as Italy’s switching sides, which meant that prospect of an invasion of Britain diminished. As a result, the policy was altered at the end of 1943, whereby from then on, all newly captured German prisoners would be taken to Britain. The numbers were overwhelming. In July 1944, as a result of Operation Overlord, PWIS(H) received some 18,000 people that month alone, all but 300 of them other ranks.³¹ In September, they interrogated almost 48,500 individuals.³² All these arrivals – some 300,000 of them by the end of the war – would go through PWIS(H) as a matter of procedure. The UK CSDIC, in contrast, interrogated 11,000 prisoners in total, over half of those in 1944 and 1945, as Figure 3.1 shows.

Figure 3.1

Prisoners handled at CSDIC(UK), September 1939–November 1945 (N = 10,758). Figures generated from information given in ‘The History of CSDIC’, WO 208/4970, TNA, Appendix C.

Figure 3.1 Long description

This stacked bar chart shows total counts by year for each branch of the Italian and German armed forces between 1939 and 1945. The x-axis shows years from 1939 to 1945. The y-axis shows total counts per category as well as combined. Each bar represents the total count per year, divided into stacked segments for individual categories. Totals rise from 169 in 1939 to a peak of 4,007 in 1944, then fall to 1,968 in 1945. Overall, total counts increase sharply in 1940s, peak in 1944, and then decline in 1945. The German Air Force, German Army, and German Navy account for most of the totals, while their Italian equivalents contribute very small numbers and only until 1943.

Thus, by the end of 1940, CSDIC in Britain became the final step on an interrogation ladder, tasked with gathering long-term intelligence such as order-of-battle plans, enemy weapons and trends in Wehrmacht recruitment, training and morale. All other potentially useful information was collected by PWIS(H), by CSDICs abroad or by field interrogators. Who would be selected for CSDIC was dictated by intelligence needs at a given moment, with ‘selection briefs’ often concerning an individual’s ‘service, unit, civilian experience, locations visited etc.’.³³

Despite being selected for CSDIC, prisoners were not always helpful, especially in the first half of the war when the prisoner population from which PWIS(H) had to choose them was limited. For instance, in 1940 the Army Section of CSDIC produced 109 interrogation reports which, with few exceptions, were each a page long. This brevity was down to prisoners’ refusal to cooperate, in some cases as a matter of principle. In other cases, refusal was explicitly down to an ideological commitment to the regime, with one prisoner declaring that Mein Kampf was his ‘Bible’, Hitler was ‘a superman’ and Jews were not worthy ‘to be allowed to live’.³⁴ In other cases refusal was down to a more general allegiance to Germany, while there were also those who claimed ignorance and wanted the war to end, often for personal reasons such as one prisoner who was about to become a father.³⁵

But when the policy of sending prisoners to the dominions was overturned, resulting in hundreds and then thousands of prisoners being sent to Britain from mid-1944 onwards, a prisoner’s willingness to talk appears to have become a selection criterion for CSDIC. And it must have been an important one, because quite a few soldiers possessed a willingness to talk yet had nothing useful to say. At the pinnacle of the interrogation system in 1944, for example, one soldier was willing to talk but had not much of interest to say as he had been a kitchen orderly.³⁶ The batman of a German general had similarly very little information to share ‘since his principal duties consisted (not unnaturally) of keeping the General’s boots polished and his rooms clean’.³⁷ To confirm that he was not feigning ignorance, CSDIC listened in to his conversations with other prisoners; he truly was clueless on military matters. Soon after, a soldier was found to be ‘exceptionally stupid and unobservant’ to his interrogator.³⁸ Other examples are a prisoner who was poor with maps, having been a milkman before the war,³⁹ and another prisoner unable to ‘read a map convincingly’ despite being taken to CSDIC precisely to pinpoint locations on a map;⁴⁰ a soldier who was previously a peasant was ‘very vague as to times, distances and places’.⁴¹ Many more were described as unobservant or unintelligent, but willing.

It follows that the fraction of prisoners that CSDIC interrogated was not exactly random. Proving this point further is the fact that some of the prisoners selected were not German, having fought with other armies before being conscripted into the Wehrmacht.⁴² We know this because with the fortunes of the Allies turning in 1943 and the resulting increase in how many prisoners they now held, CSDIC began to produce the ‘Subject Interrogation Reports’, in-depth accounts of direct interrogations, each on a specific subject. Unlike the transcripts of secretly recorded conversations, which are anonymised, these reports make brief mention to the prisoner’s particulars. A total of 1,728 such reports were produced, drawing on the direct interrogations of approximately 1,460 individuals. At least 246, or 17 per cent, of those men were either not German or part-German, a percentage disproportionate to that of non-Germans in the Wehrmacht.⁴³ They included a private from Alsace-Loraine who now wanted to join the Free French;⁴⁴ a Czech who wanted to join his national forces;⁴⁵ and a Pole who wanted to do the same.⁴⁶ Even two Russian officers were held by CSDIC at that point: one claimed to have been ‘forced by starvation into the German Army’⁴⁷ and the other was unable to help much because, ‘as a Russian, he was never kept informed of all developments by the Germans’.⁴⁸ Alongside him was a Yugoslav. And then there were those who were part-German, such as a prisoner who was English by birth and partly Jewish, and who had studied at Oxford.⁴⁹ The man interrogated alongside him was a German who had studied and worked in America for years. Three lieutenants highlight this characteristic further: one had a Swedish mother and lived abroad;⁵⁰ the other was born in Southport to an English mother;⁵¹ and the third was half Dutch – although ‘his interest in military matters was definitely weaker than his interest in the attractions of Paris night life’.⁵² A Pole was similarly ‘unobservant and not very knowledgeable’,⁵³ even though he had been sent to CSDIC from Italy. Another compatriot of his was ‘goodhearted, stupid but cooperative’,⁵⁴ a third did not speak German, so could not help with maps,⁵⁵ followed by an ‘unobservant and rather stupid Czech’.⁵⁶

The presence of deserters further indicates that willingness to cooperate was a selection criterion: 9 per cent of prisoners (127) who appear in the Subject Interrogation Reports fit this category, even though the Wehrmacht is thought to have suffered a less than 1 per cent desertion rate throughout the war.⁵⁷ Many revealed long-term reasons behind their desertion, indicating ongoing disagreement with the regime. One of them had been ‘sentenced for desertion and political unreliability’ before escaping and surrendering to the Allies;⁵⁸ a second had lived ‘in hiding in Godesberg for six months’;⁵⁹ a third had deserted two years earlier.⁶⁰ Another case was that of a non-commissioned officer who deserted in Belgium, then made his way to Italy ‘with forged papers and crossed over to the Allied lines’. Despite ending up in CSDIC, his usefulness was limited as he could not pinpoint locations on a map.⁶¹ There was also a priest who had deserted in August 1944 after been imprisoned in 1938 for anti-Nazi activities. With him was a prisoner whose uncle had been hanged for anti-Nazi activities, and another prisoner whose brother was hanged following the July Putsch of 1934.⁶² All three were selected to discuss Germany’s Indian Legion. Despite being a foreigner or a deserter not guaranteeing good intelligence, these categories of prisoner were still brought to the UK CSDIC in numbers disproportionate to those in the Wehrmacht.

The Subject Interrogation Reports were reports of direct interrogations and so of course the majority of the prisoners in them were those who willingly spoke – otherwise it was difficult to produce such a report. Still, the number of deserters and non-Germans strongly indicates that selection for CSDIC did take into account one’s attitude, at least from 1944 onwards. This is not to say that cooperation was the only criterion: rank, unit and occupation would have mattered as well. In fact, Subject Interrogation Reports exist even for non-cooperative prisoners, some of whom were considered to be anti-Nazi, thus indicating the hope that they would eventually open up. A lieutenant who was anti-Nazi was ‘at first reluctant, on account of his officer’s honour’ to talk about his Panzer Corps,⁶³ as was another anti-Nazi lieutenant who remained ‘secure on military matters’ about his infantry division.⁶⁴ A day before his capture, an anti-Nazi major was awarded the German Cross for his bravery in commanding all artillery west of Cherbourg.⁶⁵ He too refused to discuss military matters and much of the information he revealed was provided by the microphones. All of this strongly suggests that in having to choose a member of a certain unit (e.g. the Indian Legion), selectors at the various cages would have chosen the prisoner who was already talking, or the officer whose politics or experience suggested he was likely to eventually cooperate.

3.3 Means and Ends

Such cases also show once again that valuable as microphones were, direct interrogations were important: CSDIC was not simply going through the motions of interrogation only to trick prisoners into opening up in bugged cells. If anything, the Air Ministry concluded in 1945 that ‘nearly all major intelligence scoops’ they obtained were from direct interrogation.⁶⁶ Microphones would in several cases pick up useful intelligence directly, but their role in the process was to confirm the accuracy of information given in direct interrogation as well as to reveal new topics on which individuals could then be questioned. How exactly CSDIC worked was not laid out in writing, but staff often had to explain their methods to overseas headquarters setting up new CSDICs so that they could replicate the process. From one such discussion we glean some clarity into how the process worked:

The whole process was staged in order to leverage certain behaviours. Place together any two soldiers after they are interrogated, and inevitably the conversation will turn to what each was asked and what they answered – and whether it was true. ‘If [the interrogator] asks you whether you know something’, an airman was recorded advising his cellmate, ‘don’t say you don’t but rather that you cannot tell him. If it can’t be done otherwise, I simply stuff him with nonsense. I have invented phantastic “Geschwader”, “Staffeln”, “Gruppen” and numbers, and rub them under their noses’.⁶⁸ Another similarly told his cellmate that the interrogator had just asked him about ‘the nitrogen factories in Rosenheim, whereupon I pretended not to know what he meant. Of course I know, but there’s no need for him to know that’, and then proceeded to say that their location was Trostberg in Bavaria.⁶⁹ And if the two prisoners were from different services instead, soon enough they would start comparing experiences. If they were from the same service but different units, soon enough they would be discussing what equipment or tactics they were using. The secret listeners monitoring those conversations would have already been handed a brief by the interrogator, telling them what to look out for in the subsequent conversations. This way, the interrogators’ questions were answered truthfully, eventually. The listeners in the ‘M’ Room – also known as Pandora’s Box – would also monitor some direct interrogations as they took place. This too had a psychological dimension in that it allowed interrogators not to worry about taking notes as a prisoner spoke, which in turn would make the prisoner relax and speak freely, thinking that whatever he said was not considered important and would soon be forgotten.⁷⁰

Psychology was at the core of CSDIC’s work and affected every aspect of it, not just the moment of direct interrogation. In order to coax prisoners to open up even to each other, the whole environment in the camp had to put them at ease. One way in which this was achieved was the building itself, as well as its countryside surroundings. But there was also ‘matey entertainment’, which involved interrogators and prisoners going for ‘walks and amusement and expeditions outside the interrogation centre’ (‘drunken orgies’ were explicitly prohibited, though) in order to develop a more informal relationship, in the hope that the prisoner would then discuss matters of importance with them.⁷¹ Even ‘certain tree-trunks had been wired with electronic connections’, so that prisoners could be monitored when out on walks.⁷² A German soldier would have imagined all manner of scenarios of what might happen to him if captured; CSDIC’s Trent Park would not have been among them.

The psychological aspect of CSDIC and what it necessitated also became entangled with the question of what to do with a prisoner once they had to leave CSDIC, usually after one or two weeks. Prisoners could not simply be moved to regular camps, where they would compare experiences with other prisoners and begin to piece together what CSDIC was all about – and perhaps write home about it. Even prisoners who were at CSDIC and then found one another in a regular camp could compare experiences and identify stool pigeons or the topics British intelligence were interested in – and again write home about it. This was another problem tackled through improvisation under the pressure of circumstances. Although the small number of prisoners in Britain initially made this a minor issue, von Werra’s escape in 1941 turned it into a pressing concern. In the first six months following his return to Germany, CSDIC’s prisoners were marked as ‘X’ or ‘Y’, each indicating whether they had been captured before or after von Werra told his story. The idea was to separate those who may have heard of his experiences and adjust the CSDIC experience for them, so that it was unlike that of von Werra.⁷³ The segregation idea was then used for releasing these prisoners, with the X prisoners sent to a different camp to the Ys. This practice of releasing CSDIC’s prisoners into designated camps was maintained after the von Werra story faded away. The idea was that these prisoners would be kept in those camps for a few months, which would make them forget about CSDIC and minimise the security risk they posed when moved to a regular camp. The Y and X initials were also kept, though their meaning after a while had nothing to do with von Werra. ‘Y’ seems to have indicated that a prisoner was considered reliable. This is because ‘Y’ officers would be sent to Grizedale, which was used for evacuating prisoners who had given ‘material assistance’ to interrogators from July 1943 onwards. In 1944, Grizedale – which had a capacity for 300 prisoners – was replaced by a larger camp in Ascot due to the growing number of prisoners helpful to CSDIC.⁷⁴ That camp became colloquially known as the ‘Political Warfare Executive Prisoner of War camp’, since its prisoners were being used by the propaganda organisation Political Warfare Executive.⁷⁵

Another essential part of the process was the reliance on decoys – stool pigeons – who started to be used in December 1940 and talked to some 1,500 prisoners over the next five years, in conversations that were still monitored by microphones.⁷⁶ For the Admiralty, ‘converted’ Kriegsmarine prisoners were indispensable as stool pigeons: ‘almost any question which could be answered by any member of a crew of a U-boat … could be obtained within half-an-hour’ by another Kriegsmarine prisoner.⁷⁷ The other two services must have agreed because only four stool pigeons were civilian recruits; the rest – allegedly forty-nine, though possibly many more – were recruited from the existing prisoner population.⁷⁸ Other than stool pigeons, talkative prisoners would also be used to unwittingly induce others to divulge information. The combination of prisoners placed together in wired cells was therefore not always random, even in cases where stool pigeons were not involved.

The process at CSDIC was thus cyclical: interrogation was followed by secret listening to confirm the veracity of what had been said in interrogation and to identify new areas of interest; direct questioning might then occur, or indirect questioning by a stool pigeon. Microphones were part of a process rather than the entire process, a conclusion that CSDIC came to in 1940: ‘Each of the three methods employed in obtaining information, i.e. [secret recording], [stool pigeons] and direct interrogation has its special advantages, but the most satisfactory results appear to have been obtained by a combination of all three.’⁷⁹

But was all of this effort yielding intelligence, or just interesting insights of no value? The Vice Chief of the Imperial Chiefs of Staff, General Sir Robert Haining, asked this question in late 1940. To answer it, the recipients of CSDIC’s reports were asked whether these had so far been valuable. Their feedback was ‘overwhelmingly favourable from every point of view’.⁸⁰ The Director of Intelligence at the Air Ministry commented that CSDIC allowed his division – in conjunction with other sources – to be up to date with the enemy’s capacities, and in certain cases to take counter measures.⁸¹ The Director of Military Intelligence had already responded that the information obtained, although indirect, ‘had proved very valuable, both to me and to other Departments’, making specific reference to the Ministry of Economic Warfare and the Foreign Office’s Political Intelligence Department.⁸² Their counterpart in the Admiralty, Rear Admiral John Godfrey commented that ‘the actual volume of information received for the expenditure of so much time, expense and labour, has been small’.⁸³ Yet Godfrey continued that the large volume of information coming out of CSDIC only emphasised the authenticity of the source, which he thought was comparable only to photographs.⁸⁴ These views were only strengthened as the war progressed, with CSDIC’s reports being circulated to – among others – General Headquarters, Home Forces; Anti-Aircraft Command; the Intelligence Department of the Ministry of Home Security; the Political Warfare Executive; SOE; and MI5.⁸⁵ SIS were also interested in CSDIC’s work, particularly the question of whether they could recruit some of its anti-Nazi prisoners, although it was eventually decided that operating agents from prisoners of war was too risky to make it practicable.⁸⁶

Quickly viewed as the only organisation that could gain intimate knowledge of individuals’ true allegiances, regardless of their background and rank, CSDIC came to be involved not just in the collection of military intelligence but in more political tasks as well. One of them was propaganda, with CSDIC having been tasked with identifying anti-Nazi prisoners for such work. Requests originated from SO1, predecessor of the Political Warfare Executive (PWE), responsible for propaganda in enemy territory, and SO2, predecessor of SOE. The idea was born after ‘several thorough anti-Nazis’ were identified at CSDIC in 1941, ‘of whom one or two [had] expressed a wish to assist actively in the British war effort’.⁸⁷ Another was political intelligence. Topics that were generally of interest to PWE and the Foreign Office – including Germans’ faith in victory, their opinions of the BBC and living conditions in enemy territory – were being dealt with directly during interrogation at CSDIC, with PWE on the distribution list of their reports. Once the fortunes of the war began to change, another area that rose to prominence was psychiatric research into German morale. The head of the Directorate of Army Psychiatry, a War Office department, met PWE in 1942 to discuss the development of ‘psychological warfare’,⁸⁸ and soon after he met staff at CSDIC to discuss the possibility of a psychiatrist moving there to do propaganda-related research with prisoners of war, in order to gain a more scientific understanding of German morale.⁸⁹ With the intensification of propaganda efforts at that stage, such was the value of CSDIC to PWE that from January 1943 onwards, representatives of both would meet every second Friday of each month to discuss what information was needed from prisoners for propaganda purposes.⁹⁰

Another instance that reinforced the importance of CSDIC was the reaction when its work came under threat. Like the Tower of London before it, Trent Park was found to be less than ideal; its location near the capital meant that it would possibly need to be evacuated (or worse, it would be bombed).⁹¹ Two new buildings were requisitioned to replace it in 1941, each offering over thirty rooms for bugging compared with Trent Park’s twelve. At around the same time however, the Air Ministry was preparing to build an aerodrome near the new premises, the noise from which would render CSDIC’s work impossible. In the ensuing stand-off between the Air Ministry and the War Office, the intelligence divisions of the three services concurred. Arguing against his ministerial colleagues, Director of Intelligence Air Commodore Archie Boyle wrote that CSDIC’s value had already been justified, the information obtained had been ‘inestimable’ and nothing ought to stand in the way of its continued functioning.⁹² Of the same opinion was the Admiralty’s Godfrey: CSDIC was of ‘such operational importance as to make it vital to develop this source of information to the full’.⁹³ The case was put to the chiefs of staff, who concluded that CSDIC was ‘of the utmost operational importance, vital to the needs of the three fighting Services’ and ‘its requirements should be given the highest degree of priority’.⁹⁴ Plans for the aerodrome were duly scrapped, and prisoners were moved to the new camp (Latimer House in Buckinghamshire) in July 1942, and to the second, smaller camp (Wilton Park in nearby Beaconsfield) later that year.⁹⁵

Trent Park in Cockfosters was nevertheless not abandoned. It remained a CSDIC camp even after 1942 to house prisoners of the rank of general who started to arrive from North Africa in August 1942; the first such prisoner was Ludwig Crüwell, followed by Ritter von Thoma in November.⁹⁶ The idea of interrogating them in Britain – or anyone above the rank of colonel – was not really entertained, both because these prisoners were unlikely to say much under interrogation and because there were no interrogators holding a corresponding rank. It is here that secret listening emerged as the only method at CSDIC’s disposal, though once again psychology could be used to generate interesting discussions. This did not prove to require much effort. Even when the two generals were the only ones in Trent Park, it became clear that they had interesting insights to offer. What was specifically noticed once Crüwell and Thoma started to converse was that they had different views towards the conduct of the war. In a conversation triggered by the capture of Field Marshall Paulus in Stalingrad in early 1943, Thoma told the more reserved Crüwell: ‘I am firmly convinced that it is not due to the stupidity of our soldiers and the General Staff [that we are losing the war on the Eastern Front] but because the FÜHRER simply looks at the map and say [sic]: “No – no – no – no – no!” I know him’.⁹⁷ In a later conversation about atrocities in Minsk, Thoma was again more critical of what was happening:

As others started to arrive at Trent Park, they would gather around the two generals according to their politics, this way forming two cliques. Those critical of the regime would gather around Thoma (many of them, like Thoma, still made antisemitic comments even when they disagreed with the regime’s decisions), the others around Crüwell.⁹⁹ In the absence of other methods, fostering this division became a way to generate useful discussions. And so various events would be staged in order to exploit their existing rivalries and provoke their reactions. For instance, an artist was once commissioned to draw portraits of the generals. The Crüwell clique rejected the idea of any one of them sitting for a portrait. The Thoma clique accordingly accepted it and Thoma not only had his portrait painted, he was also allowed to visit the artist’s studio to see it, precisely so that the rival clique ‘would be provoked into jealous discussion, with possible interesting results’.¹⁰⁰ This subtle divide and rule, which was exploited rather than created, was seen as worthwhile, even by Churchill. When he first found out in March 1943 that prisoners were treated in this way – taken out for walks and on day-trips – he was furious: ‘What is the truth about the tales I hear of applications by SOE or PWE or some other body for the leading captured Generals to … be taken about the country to see things? There was an idea, for instance, that General Messe should visit Eton. I should be opposed to any of this nonsense.’¹⁰¹ Yet it was after one such outing that Crüwell unknowingly elicited ‘invaluable information on submarine tactics’ from another prisoner.¹⁰² A walk had turned a German general into Britain’s ‘best interrogator’, and so Crüwell was kept at Trent Park for nearly 700 days before being dispatched to the United States in 1944. The Joint Intelligence Sub-Committee (JIC) intervened to explain to Churchill the necessity of these tricks, with him then agreeing to such treatment. He even requested that reports of discussions between generals following such outings be sent to him.¹⁰³

Not only were CSDIC’s methods known and condoned by the top tier of government, they were also on occasion directly encouraged. One such occasion was from mid-1944 when the JIC instructed CSDIC to gauge how the generals responded to the topic of a ‘Free German Movement’. Only months earlier, the Soviet-sponsored ‘National Committee for a Free Germany’ had been formed by Walther von Seydlitz-Kurzbach, a German general who defected to the East in 1943, and he was specifically mentioned in this instruction to CSDIC. Could there be a von Seydlitz-Kurzbach in Britain? To find out, CSDIC was instructed to ‘sound out the possibilities but no commitments to be made’ to any of the generals who showed an interest. Soon after, CSDIC reported that ‘several specially arranged interviews were devised [in May 1944] with those Generals who showed themselves most willing to co-operate’.¹⁰⁴ Not much seems to have happened on the topic and the value of the generals to Britain was, on the whole, indirect rather than direct – it was how those generals saw the war’s course and conduct as well as how they judged each other that proved priceless to British intelligence, rather than their usefulness for other tasks.¹⁰⁵

3.4 Staff

The rough version of CSDIC that started out in the Tower of London was soon honed into an efficient and versatile process, concerned not only with military facts but also the war’s political, propaganda and social scientific realms. Much of this transformation was enabled by the administrative changes that took place in 1940 – shifting it from MI1 to MI9 – which allowed more focused attention and resources to be given to CSDIC. This was also happening at a time when the intelligence system overall was becoming better coordinated and began to produce a stream of information that was comprehensive enough to allow interpretations drawn from it to be ‘generally correct’.¹⁰⁶ But even those administrative changes were the work of the few who were initially based in the Tower and who articulated what needed to change to make this experiment work. There was much that was unique about the staff of CSDIC, but two characteristics stand out. The first is the linguistic aspect, which was integral to the interrogations’ functioning. In practice, this meant that about a third of CSDIC’s staff were not British, and many of those who were spoke at least one other language, that usually being German. The second was the desirability of drawing CSDIC’s staff ‘from personnel unfit or ineligible for general service’, as with other operations that were based in Britain.¹⁰⁷ Together, these meant that it was women, refugees, veterans of the previous war and anti-Nazi soldiers that really honed the art of British interrogation.

Women were part of CSDIC from day one, with two of them having served on the six-strong intelligence team in the Tower of London as shorthand writers and linguists. From then on, and as CSDIC kept growing – from a few dozen staff at the start of the war to 1,000 in 1942 – the female Auxiliary Territorial Service (ATS) accounted for about a quarter of the establishment (Table 3.1). A document setting out the duties of four female junior commanders lists them as liaison officers, responsible for maintaining the war diary, updating the registry and distributing the reports. Yet women were not only tasked with general camp duties: a quarter of CSDIC’s intelligence section was female as well. We know, for instance, that it was almost always women translating the recorded conversations from German into English and compiling ‘glossaries of technical and slang terms’.¹⁰⁸ Given these duties, we can assume that many of them were German-speaking émigrés fleeing the Nazis, such as Susanne Cohn, who was also Jewish.¹⁰⁹ It is also likely that more German women worked in CSDIC considering that from 1941, Germans and Austrians could join the ATS.¹¹⁰

Interrogators were always men, and so were the prisoners; only one woman has been identified as having passed through CSDIC in the UK. Hauptführerin Elise Kirsch was a Nazi Party member who ‘talked willingly and indeed didactically’ about the women’s clerical service, to which she belonged.¹¹¹ The role of interrogators was instrumental. They decided how to obtain intelligence from a specific prisoner and then instructed secret listeners and decoys on what to do. There was one crucial aspect in which they had no say, though: what intelligence to report, and how. They were instead instructed to report what a prisoner said in interrogation as faithfully as possible rather than to try to interpret it, and to be as factual as possible when it came to commenting on whether or not they thought the prisoner was being honest. This was to limit biases; after all, interrogators were as fallible to mind tricks as their prisoners.¹¹²

Interrogators were also the only members of CSDIC’s intelligence team who would come face to face with prisoners; the secret listeners never did, and decoys were obviously under cover. In those interactions, their job did not involve ‘putting the fear of God into the prisoner’ or using force.¹¹³ Instead, the interrogator’s job revolved around a mind game: trick the prisoner into giving information without realising that they were doing so, ‘by virtue of the fact that the interrogator [was] a master, or sufficiently informed to make himself appear the master, of a subject of interrogation’.¹¹⁴ To achieve this, an interrogator would consult what was known as his ‘bible’ before questioning a prisoner – this was made up of the prisoner’s recorded conversations, any assessments that stool pigeons had written about him, the prisoner’s correspondence and captured documents. Nor were the other activities in CSDIC separate from interrogation; rather, they were all a continuation of it:

All of this was learned on the job. There was a short training course for interrogators – mainly to introduce them to the structures of the German armed forces – but the relevant skills could only be mastered in practice. This would usually happen first in the cages of PWIS(H), where interrogators not only gained practical experience but became accustomed to being ‘face to face with a truculent Boche’.¹¹⁶ As for the kind of person selected for this task, preferences varied but they were not always military men. The Naval Section of CSDIC, for example, discovered that ‘lawyers and scholars used to sorting out masses of unfamiliar evidence, journalists and business men trained to warm their way into new situations’ made good interrogators.¹¹⁷ Lack of military training may have nonetheless exacerbated an existing problem, namely the inaccuracy of the documents CSDIC relied on. This problem was identified by the Military Intelligence Research Station, a War Office organisation analysing captured documents. Problems emanated from the Soldbuch carried by prisoners and on which CSDIC relied for their interrogation. Yet entries in a Soldbuch were made by German non-commissioned officers and errors were frequent.¹¹⁸ Interrogators would often replicate those errors due to their lack of specialist knowledge.

And while it has been mentioned that many of CSDIC’s staff were not British, they were not drawn from the Allied governments-in-exile but rather from refugee and immigrant populations directly. This was because there was reluctance to involve any European Allies in CSDIC or share with them the intelligence obtained. The aversion was not extended to US intelligence, whose representatives visited CSDIC and which received CSDIC’s reports from 1942 onwards (this included the US Navy, the Headquarters of the European Theatre of Operations USA and later the US War Department).¹¹⁹ On the rare occasion that the European Allies had to become involved, this would happen at the PWIS(H) cages rather than CSDIC. One such occasion took place in the spring of 1943, when three Free French interrogators were allowed to come to the London Cage to interrogate the survivors of a U-boat. It was made clear to them that this permission was exceptional and ‘a matter of courtesy only’.¹²⁰ The aversion to the French in particular was maintained even in 1945, when it was suspected that the French were about to request access to intelligence obtained from naval prisoners; the line was then repeated that the ‘Chiefs of Staff have already laid down that the secrets of our own technical knowledge are not to be divulged to the French’.¹²¹

One reason for this opposition to the French being present in CSDIC – which was shared by the JIC – was blamed on the suspicion that the French would use violence.¹²² When in 1939 a British officer was sent to observe his French counterparts interrogate, the verdict was that Britain had ‘little to learn from the French, whose harsher methods would not suit the British mentality’.¹²³ The fact that de Gaulle’s men had been accused of ill-treating French citizens in their London headquarters did nothing to help this view.¹²⁴ The assumption that non-British interrogators would use ‘un-British’ methods extended to the Poles as well. The language skills of Polish personnel were needed when prisoners who were ethnic German or otherwise made to join the Wehrmacht from annexed territories awaited interrogation. And so there was more flexibility in employing them at PWIS(H) level. No sooner than the first two Polish interrogators arrived to assume duties in a cage in 1941 however, the officer in charge wrote to Alexander Scotland to say that ‘their ideas on the physical handling of [prisoners] are obviously not ours’. The men neither did nor said anything to confirm this view, and it was the officer who inferred that this was their intention: ‘although they did not say so in as many words, they were obviously expecting me to tell them what bludgeons and wrist-twisting gadgets were available for use on recalcitrant prisoners’.¹²⁵ By the end of 1941, seven Poles were working in PWIS(H), interrogating prisoners in the presence of a British officer to ensure good treatment.¹²⁶

Together with his own linguistic skills, the performance of a CSDIC interrogator relied much on eavesdropping, which was, in turn, dependant on the skill of the people executing it. Secret listening was initially the domain of bilingual British officers.¹²⁷ Because there were not enough of them to meet the increasing demand, and because they often spoke academic German, meaning they could not always understand local dialects and slang, they came to be supported by the Pioneer Corps, which was made up of Germans and Austrians who had fled Europe, many of them Jewish. These individuals were vetted by MI5 and JIC before being sent to CSDIC, which found them to be so adept at the task that it was suggested that the number of British officers involved should be decreased and replaced with Pioneer Corps staff. By 1943, the ‘M’ room would be run almost entirely by them.¹²⁸

However, while secret listeners were critical, they could only do so much if useful discussions did not occur. This is where stool pigeons played their part. Even Trent Park’s generals had a stool pigeon. Unlike in the usual process, where any man fluent in German and willing to work for Britain could be introduced as a fellow soldier to a genuine prisoner, it was impossible to introduce fake senior ranks to actual German generals. For this reason, an intelligence officer, Ian Munroe, was tasked with pretending to be a ‘Welfare Officer’, there to ensure that the generals’ detention was a comfortable one. To gain their trust, Munroe was introduced as ‘Lord Aberfeldy’, an aristocrat, when in reality he did not have a noble background. The trick worked. Theodor von Sponeck, who was kept in the camp for 480 days, wrote in his memoirs that he did not suspect Munroe to have been an intelligence officer.

When it came to selecting decoys, these also had to be native German speakers, good at assessing personalities and would ideally have had experience outside Nazi Germany.¹²⁹ The few – most likely four – civilian recruits were refugees, recommended to CSDIC by MI5 who were interrogating civilians escaping to Britain from the Continent. Their job was to blend in: to appear as nothing more than prisoners awaiting interrogation. Yet what these people had lived through, and continued to live through, was anything but ordinary. One of them was Theodore (Bill) Barazetti, born in Switzerland in 1914.¹³⁰ After helping to evacuate trainloads of Jewish children to London from German-occupied Prague in 1939, Barazetti was interned by the Gestapo but escaped to London later that year. It was then that he started work at CSDIC. Another stool pigeon was Josef Lampersberger, an anti-Nazi German whose citizenship had been revoked due to his activities with the Social Democrat Party. Like Barazetti, Lampersberger had been interned by the Gestapo, and had previously worked for the Czech Intelligence Service.¹³¹ A third man had been an anti-Nazi policeman in Hamburg until his escape from Germany in 1941. So adamant were MI5 and MI9 that he should work for CSDIC that despite being sent to Canada due to a miscommunication, he was sent back.¹³² The majority of decoys were, however, anti-Nazi German prisoners of war. The despair they must have felt while ‘on the job’ is hard to imagine. Decoys were selected for their defiance of the regime yet now had to sit across soldiers who often supported it and discuss the war without emotion. They must have also been nervous at the prospect of being identified as working for the British. Their mental state after such discussions is indicated by their being subject to what was described as ‘extreme nervous tension’ and ‘severe stomach disorders’, and so a doctor was always on call to visit them.¹³³ This burden must also have been carried by those doing the secret listening and translating the conversations into English.

The people of CSDIC were vital to how the organisation’s process evolved. Their accelerated promotions suggest that the leadership was important too. Within two years of taking charge, CSDIC’s Commandant, Thomas Kendrick, went from captain to colonel.¹³⁴ When Arthur Rawlinson was taken out of the reserve he was captain, but was promoted almost immediately to acting major upon being assigned the task of helping CSDIC liaise with the three service ministries,¹³⁵ and to temporary lieutenant colonel in 1941. The hierarchical standing of CSDIC altogether was gradually upgraded. It went from the inadequate set-up of MI1 to being part of an expert department, MI9. Within less than two years, by 1942 CSDIC and PWIS(H)’s activities had massively expanded; the other side of the MI9 coin (intelligence to and from British prisoners of war) also had an increasing and important workload, making it doubly difficult for MI9 to continue as one unit.¹³⁶ For this reason, each operation was split into two separate units: MI9 continued to deal with British prisoners of war, while CSDIC and PWIS(H) became part of a new section, MI19.¹³⁷ Put simply, from 1942 onwards enemy prisoner intelligence was a separate sub-section of the War Office.¹³⁸

Hierarchy, numbers or duties – by whatever standard we look at it, the development of CSDIC during the war was extraordinary. While it was established with the intention of eavesdropping for stand-alone pieces of information, it had to expand precisely because eavesdropping on its own proved to be insufficient. As part of this realisation and because of the course of the war, CSDIC in the UK became the final step in an elaborate system which processed hundreds of thousands of soldiers and then selected a cohort for these bugged camps. At the centre of CSDIC were refugees and immigrants, the women of the ATS, anti-Nazi German soldiers and Britons, many of them veterans who had been taken out of civilian life and into CSDIC. That their work was never interrupted, not even after Franz von Werra’s unlikely escape, is testimony to their processes having worked. For all its value to both intelligence and posterity, the vast material they produced must have had an enormous impact on all involved. Yet this impact had to stay muted. Having been sworn to secrecy, many of CSDIC’s staff kept their experiences to themselves and others only shared them decades later.

When Kendrick and Rawlinson closed the camp down on 7 November 1945 – with all their staff now redeployed and the premises handed over to new occupants – they had much reason to take (quiet) pride in what they had achieved. The following day, 8 November, MI19 ceased to exist on paper as well.¹³⁹ It was as if nothing had ever happened. This was the predominant impression even within the official apparatus. Over a decade after his stool pigeon work in CSDIC had ended, Lampersberger, now a naturalised British citizen, wrote to the Home Office to ask if his Polish parents-in-law could be allowed into the country, where all their relatives now lived. After his application was rejected twice, and in a bid of despair, he finally hinted at his wartime work: ‘I base this appeal on … [the] Service I have given to this country between the years 1940–45 in a confidential matter of which I have never made any use of’, he wrote.¹⁴⁰ It took weeks for the Home Office of the mid-1950s to establish what work that was. Whatever information they managed to find led to the conclusion that Lampersberger ‘was engaged as an interpreter’, a service not considered important enough to merit a relaxation of immigration rules.