Attempting the biography of a living person is a risky business, as was shown by the biography of Robert Runcie. How the book itself should be received was made even more problematic by Runcie's acknowledgement that he had cooperated with his biographer. Over the last few years, there has been a growing number of Ph.D.s on my father's theology. Each contains the obligatory biographical chapter, usually taking in each other's washing, and referring to a published interview my father once had with Robert Palma. One couldn't blame them: for so forthright a theologian, my father is a surprisingly private person, suspicious of psychologising and what he called ‘subjectivity’. When Alister McGrath announced that he planned a biography, I welcomed it. His industry was legendary, but, as important, he was neither an avowed ‘disciple’ nor a former student. Most of all, I dreaded something creepily sycophantic. In all of this, Alister McGrath's book does not disappoint. As a biographer, he was a gentleman and kept his distance. He did not burden my father with emails, nor did he attempt to become one of the family or solicit academic references for himself. In response, we treated him as a friend and trusted him with documents, photographs and letters – and documents must still be the academic biographer's bread and butter, not taped conversation, flattery and guesswork. Consequently, this book is, by and large, defensible by reference to its sources and clear in its narrative. Even I learned more about my father from it.

The choice of genre is important and determines the content of the book. McGrath makes clear in his introduction (p. xiii) that he attempted an ‘intellectual biography’. He suggested one should regard my father primarily as a man of ideas, and so largely eschewed the matter of traditional biography – family life and personal relationships. Roughly 110 pages are spent on biographical narrative and then another 130 are devoted to outlining the theology. The section on early life in China is short but documented. Even as a son, I have so often asked myself, ‘Why did he write so much?’ ‘Whence came this vision?’. Ultimately, these are unanswerable questions, but China, I am sure, is important. McGrath ends the story by describing my father's subsequent returns to his homeland, movingly including a photograph of the ageing theologian, together with a group of Xiang Christians, including a survivor from his childhood days and a young mother with her baby. There is actually a mistake here in McGrath's text and the visits have become conflated. My father returned to China three times, not twice. The visits were 22 March–12 April 1984, 1–28 October 1986 and 21 April–4 June 1994. McGrath goes on to give an account of study at Edinburgh University, under A. E. Taylor and Norman Kemp Smith in philosophy (which formally initiated my father's lifelong fascination with issues relating to realism and reference) and H. R. Mackintosh and John Baillie. An important source here was my father's detailed manuscript notes (almost 100 pages) on Mackintosh's lectures on dogmatic theology. McGrath goes on to describe early travels in the Middle East, which contributed to an abiding love for the Jews and insistence on the importance of Judaism, initial study under Karl Barth and my father's unexpected appointment to Auburn Theological Seminary in 1938–9. The typed lectures prepared for Auburn – never before allowed into someone else's hands – provide another hitherto unquarried documentary source. After the year in Auburn, McGrath points to one of the book's intriguing ‘What ifs’. In June 1939, my father was offered a chair at Princeton University. He declined it (Brunner said to him, ‘I think you and I ought to return before the submarines start’) but what if he had accepted it and stayed? It amused my father that more than sixty years later I am in Princeton.

The war came, and with it service as a chaplain and the unforgettable pastoral experience of ministering to those who are exhausted and afraid. Even at this stage he was exercised with the relation of theology to science, and gave some lectures (only one survives) to fellow chaplains at Assisi. Subsequently, there came marriage to Margaret Spear, pastoral ministry in Alyth and Aberdeen, children and the move to New College, Edinburgh, in 1950. The account of the period in Alyth and Aberdeen is informed intellectually not only by the publication of The Doctrine of Grace in the Apostolic Fathers (1946 and 1948) and Calvin's Doctrine of Man (1949) but also by my father's manuscript sermons from 1940–50. These (hundreds of them, tidily kept in brown envelopes, each with its date of delivery) were given to me by my father just days before I embarked on parish ministry in Shetland, and had been seen by no one else before McGrath.

The account of the Edinburgh period is, I think, the book's Achilles’ heel. The bones, of course, are all there: the theological flowering, the editing of Barth's Church Dogmatics, the establishment and growth in influence of Scottish Journal of Theology, the engagement in ecumenical dialogue, the convenership of the Commission on Baptism for the Church of Scotland, the dialogue with science, the call to be Moderator of the Church of Scotland's General Assembly and the Templeton Prize. There is the most intriguing ‘What if’ of all: the invitation to succeed Karl Barth in Basel (documented by an urgent manuscript letter from Oscar Cullmann). But it is all rather unidimensional and monochrome. And this is where one wonders if Alister McGrath's shrewdly chosen, but letter-box narrow perspective of ‘intellectual biography’ finally lets him down. It does not adequately deal with the complication and richness of other people. Without in the slightest sense diminishing my father's achievements, there were other people involved. The Church Dogmatics were edited with Geoffrey Bromiley, SJT was edited with J. K. S. Reid, the secretary of the Baptism Commission (the Church of Scotland's most sustained engagement with doctrine since the Second World War) was John Heron (Alasdair Heron's father). There were brilliant and different colleagues (John Zizioulas, Roland Walls, James Torrance and Alasdair Heron). Long-lasting colleagueships, like long marriages, are very interesting – the ability to sustain a human relationship through ups and downs. Most significantly, there was my mother, without whose stability and faith my father's work is unthinkable. Yet she is completely ignored, as is my brother, Thomas, whose sheer intellectual clarity made a persistent but unsung contribution to our father's writing, thinking and interests for decades.

Alister McGrath presents as his third ‘What if’ the principalship of New College. In fact, I find this, on reflection, unconvincing. My father has always loathed academic administration. My brother and I sometimes amusedly wonder how he would have coped in the nightmare of modern British university life. (But, of course, he wouldn't: he would have moved at once to the US.) I can understand the ‘What if’ about Princeton and Basel. I have never been entirely sure why we didn't move to Switzerland. But the principalship of New College, as a real possibility, leaves me cold. The trouble is that the story, thereafter told far too simply, presents John McIntyre unfairly as a second-choice principal and then damns him on several counts, at least by implication. We have to remember that the ‘What ifs’ are only a literary device. And this way of telling the story caused hurt to John McIntyre and did him injustice. It is suggested, for example, that a shift away from Christian Dogmatics and a move into Religious Studies was part of an agenda of McIntyre's and led to an impoverishment of New College. That is such a very partial telling of an extremely complicated situation that it can only be considered as a slur. All the ancient Scottish Faculties of Divinity (Aberdeen, Glasgow and St Andrews as well as Edinburgh) smoothed the way for Religious Studies as funding is now determined more by student numbers than by block grant. Yes, the Edinburgh Dogmatics Department did break up, but this was because all its former members moved to chairs elsewhere, and then general financial stringency made replacement difficult. Yet, even so, Reformed doctrine continued without a break to be taught at Edinburgh, by such distinguished players as David Fergusson, Bruce McCormack and Gary Badcock. And David Fergusson, to the delight of both my father and John McIntyre, now succeeds them both in the new single chair of Divinity.

One can sympathise with McGrath. For certain sections of his life, my father wrote autobiographical chapters. These covered his various visits to China, his visit to the Middle East in 1936, Auburn in 1938–9, student years in Edinburgh and Basel, war service, parish ministry in Alyth 1940–3. These are unpublished (though so circulated and reproduced in theses that they might as well be). But there is no account of the Edinburgh years. Even if there were, we would only have the testimony of one voice, and the politics of New College, for decades, were labyrinthine. As a very small child, I remember my father coming home and telling my mother of an occasion when James S. Stewart had wept at a faculty meeting. There were, of course, differences in personality, perspective and strengths between my father and John McIntyre. There always are between colleagues. But I believe it may truly be said that they always maintained cordiality and that their wives (my mother and Jan McIntyre) were the best of friends. Again we see the difficulty and risks of contemporary biography. Distance and documents allow us to make better assessments.

Alister McGrath's otherwise excellent and sure-footed biography is completed with an invaluable 46-page bibliography of my father's publications from 1941 to 1999. The new paperback version of the 1999 edition is now adorned on its cover and spine by Luke Watson's photograph of my father at the age of 90 at Christmas 2003.