As a celebration of the lifetime achievements of one of Britain’s greatest castellologists, this magnificent volume of tribute essays from his friends, colleagues and peers reflects the breadth, depth and multi-faceted diversity that has characterised the work of Derek Renn. With a brief introduction by Neil Guy and longer retrospective by the late Charles Coulson, its eighteen main papers encompass the whole of the British Isles and the Angevin homelands that were the main focus of Derek’s research over the last sixty-two years. Chronologically, the primary focus spans the eleventh to late fifteenth centuries, with studies covering individual structures or groups that illustrate the developments of castles as artefact and concept. Reflecting Derek’s own approach to castle studies, however, there is as much discussion of the builders and patrons, the sociology and psychology of castle design and construction that serves to humanise and contextualise the subject-matter. This is no mere series of architectural or art historical papers dealing in abstracts, but a collection of crafted studies that underscore the revolution that has occurred in British castellology over recent decades.

From this rich collection, comment on three of the contributions must suffice as illustrations of the overall quality of the intellectual feast on offer. One of Derek Renn’s enduring passions has been medieval siege engineering and castles’ defensive capabilities. In his paper on the origins, evolution and impact of the trebuchet, Peter Purton focuses on Derek’s enduring interest in military technology, and castle-breaking siege engines in particular. Reviewing the origins of the stone-throwing siege engine and debunking many of the semi-popular myths that have arisen from academic (non-physics/engineering tested) hypotheses, Purton strips out myth accretion around the stone-throwing engines of the twelfth century and reveals that in most cases where engines were presented as wall-destroyers it was, in fact, miners who brought down the defences. But then there was a step-change and from the 1190s onwards it seems that technological development had increased the range and impact of the engines to such an extent that they became decisive elements in siege-winning arsenals. It appears that the gunpowder revolution, often argued as presaging the end of the castle, had a precursor in the counterweight-and-throwing arm revolution of the late twelfth and early thirteenth centuries. That hypothesis is gently presented, but it has an impact as effective as the thirteenth-century trebuchet. It leads Purton to end with a revising of recent revisionism, floating the possibility that the significant changes in castle design that are evident from the early thirteenth century were, in fact, a response to the threat posed by the new and more potent siege engines that had been developed in the later twelfth century. Design, he posits, might have more to do with response to technological change than many of us might recently have argued. It is, he concludes, a subject that demands further investigation.

Neil Ludlow’s forensic analysis of the donjon at Bothwell, and the unfinished enclosure of which it was the dominant part, is one of this volume’s highlights. This structure has been one of the icons in the traditional narrative of Scotland’s later thirteenth-century ‘Golden Age’, usually with the donjon of Coucy regularly cited as its inspirational source but with no evidence offered beyond that bald assertion. Ludlow has cut through the often self-referential historiography underpinning that narrative and undertaken a re-analysis of Bothwell that goes back to the physical evidence, freed from the teleological straitjacket of Coucy-based comparisons and firm association with the Murray family as its late thirteenth-century builders. He focuses instead on the grant of Bothwell after 1296 to Aymer de Valence, earl of Pembroke, and the donjon’s more obvious architectural affinities with the cylindrical donjons of the Welsh Marches. Valence is presented as a more obvious patron and, using Derek Renn’s calculation of likely heights achieved during seasonal building operations, Ludlow suggests that the donjon’s relatively low height to diameter ratio supports the probability that construction spanned only some nine seasons before the earl lost possession of the lordship of Bothwell. Pushing construction forward into the early fourteenth century is revolutionary enough, as there is exceptionally limited evidence surviving for major building operations at any Scottish castle during this first phase of the Scottish Wars of Independence, but assigning its building to one of Edward i’s chief lieutenants rather than the Scottish Murrays overturns 150 years of historiographical convention. An icon of thirteenth-century Scotland’s assertive national self-confidence has become instead a symbol of how close the kingdom’s medieval independence came to extinction.

Unconformity of design and how to interpret that in buildings erected contemporaneously and for the same patron is the central question of Philip Dixon’s excellent study of ‘Patron and Builder’. Underpinning it is the sub-question of ‘how much of the finished result was due to the patron and how much to the architect, the master mason?’. Certain pointers to the key role of the latter can be seen in examples such as Newark and Sherborne, the former built for Bishop Alexander of Lincoln, the latter constructed for his uncle, Bishop Roger of Salisbury, where the surviving gatehouses display strikingly close parallels with each other. Sufficient evidence exists in buildings such as Malmesbury Abbey, which was under Bishop Roger’s patronage, to suggest that his diocese was the source of the architectural inspiration in Bishop Alexander’s castle. The connection is not the two men’s kinship per se, but the possibility that Bishop Roger sent some of his key building-operatives to assist his nephew at Newark. Sadly, however, we do not have the name of the master mason to enable us to strengthen that link further. In the great towers at Newcastle and Dover, however, built for the same patron (King Henry ii) and probably by the same master (Maurice cementarius or ingeniator), Dixon finds the opportunity to test the builder vs patron tension and edge towards answering a question that has exercised him for over fifty years. The conclusion may be ultimately a frustrating set of maybes, but what Dixon presents to us is a scenario in which the patron presented a series of symbolic, space and function requirements specific to the castle in question and the architect delivering a solution that accommodated those needs in a fashionable physical format. His final statement may seem a simple point to make: that to understand better the variation in form between the products of the same hand for the same patron, we need to understand the principal requirements of the patrons at the time of their construction. Dover and Newcastle were both about physical projection of power and status through the form and fabric of a structure, but one had aggressive diplomacy and hospitality-with-attitude at its heart, while the other was a blunt instrument that proclaimed one ruler’s possession in the face of another’s disappointed claims.

Rich, wide-ranging and thought-provoking, this is a magnificent mark of a whole field of scholarship’s acknowledged debt to a master. It has some flaws, particularly its manifold variety in note forms and abbreviations, but these are minor alongside the wealth of inspirational analysis, hypothesis-building and straightforward calls for more research that it contains. And through it all runs one constant leitmotif, the remarkable contribution of Derek Renn to our still-unfolding understanding of castles.