IN THE March 2013 issue of The Pink Humanist I reviewed Turing: Pioneer of the Information Age, a new biography of Alan Turing by Jack Copeland. I mentioned three existing biographies – Alan M. Turing (1959) by Alan’s mother Sara Turing, the epic Alan Turing: the Enigma (1983) by Andrew Hodges, and The Man Who Knew Too Much (2006) by David Leavitt – and I posed the question of what value another biography provides.

That question arises again with the publication of this latest biography, Prof: Alan Turing Decoded, by Dermot Turing. This time the author is more forthcoming. Unlike Jack Copeland, he pays full tribute to Andrew Hodges’s “masterly” biography at the outset. However, his aim and perspective are rather different.

He has been reported as saying that his main aim in writing the book was to challenge some widespread stereotypes about Alan Turing’s life. In his epilogue he points out that most people’s impressions are likely to be formed from portrayals such as those of Derek Jacobi (in the 1986 play and 1996 television film Breaking the Code), Ed Stoppard (in the 2011 television docudrama Britain’s Greatest Codebreaker, later released internationally as Codebreaker) and most recently Benedict Cumberbatch (in the 2014 film The Imitation Game). No doubt the last of these, with its gross exaggeration of Alan’s autistic tendencies, would be a particular incentive for him to want to describe the real man behind the myth.

Dermot Turing’s perspective is that of one of Alan Turing’s closest living relatives, being the son of Alan’s brother John with his second wife Beryl. Unlike his half-sisters, Dermot was born too late to have known Alan personally. However, his father, who died in 1983, was one of the few people to have known Alan well throughout his life, and one of even fewer to have read Alan’s “dream books”, the notebooks in which he recorded his dreams for his psychotherapist during his last months.

Dermot makes use of his father’s papers, including his essay My Brother Alan (not published until 2012 when it appeared as an addendum to a new edition of his mother’s 1959 biography) and his full-length autobiography The Half Was Not Told Me (1967), which remains unpublished. Rather oddly, Dermot follows his father in dating Alan’s birth as 21 June 1912, when the rest of the world (including Alan’s own mother) thinks it was 23 June.

The challenge facing any writer following in the footsteps of such a thorough and enduring work as Alan Turing: the Enigma is to produce a full and balanced biography and yet still have something fresh to say. Dermot Turing’s approach to this is to pay particular attention to evidence that has come to light in recent years. Andrew Hodges has been tracking these developments too, of course – both on his Alan Turing Website and in prefaces to successive new print editions of his book, last reissued in November 2014 to coincide with the release of The Imitation Game – but Dermot Turing has had the opportunity to weave it all into a single coherent narrative.

On the one hand, the Government Communications Headquarters (GCHQ) – the successor to the wartime Bletchley Park organisation that Alan Turing worked for – continues to release relevant papers from its secret archives from time to time. GCHQ has co-operated with this book, not only by permitting use of some as yet unreleased material but also by hosting an unprecedented launch event for the book at its Cheltenham headquarters in October.

On the other hand, new information still emerges from private hands – or heads – from time to time. For example, in 2011 the writer Alan Garner recalled conversations he had with Alan Turing in the early 1950s, unexpectedly reinforcing Andrew Hodges’s long-held view that Alan was fascinated by the story of Snow White and the poisoned apple. More recently, following the death of Alan’s close friend Nick Furbank last year, three letters that Alan wrote to him surfaced just in time to be quoted in the book.

Around the time The Imitation Game was released, the genealogy organisation Ancestry placed a story in the press claiming that Benedict Cumberbatch is a 17th cousin of Alan Turing. More interesting, to my mind, is that the supporting pedigree presents Alan as a direct descendant of King Henry VII of England. Dermot Turing has wisely avoided delving so deep but he understandably starts his book with a little more family history than some biographers provide.

Rather than dwell on the Turing baronetcy (which he himself currently holds after inheriting it from a third cousin once removed in 1987 – hence his official designation Sir John Dermot Turing), he follows Alan’s mother in mentioning some of the more eminent scientific brains of the family, who happen to be on her side. They include the physicist George Johnstone Stoney FRS, three of his children – George Gerald Stoney FRS (engineer), Edith Anne Stoney (physicist) and Florence Stoney (radiologist) – and his brother Bindon Blood Stoney FRS (engineer).

The book’s account of Alan Turing’s life pretty well follows the familiar sequence, with careful attention to less familiar parts such as his work on speech encipherment during the latter part of the Second World War. It includes the two episodes that throw most light on his sexuality – the death of Christopher Morcom in 1930, and Alan’s brush with the law in 1952. It’s interesting to read Dermot’s comments, as a qualified solicitor, on the way Alan was treated by the judicial system.

Like others before him, Dermot considers the enigma of whether Alan’s death was deliberate or accidental. Speaking after publication of the book, he is reported as saying he doesn’t believe it was an accident, but in the book itself he remains studiously neutral, concluding by quoting words attributed to Alan’s closest friend, Robin Gandy: “Some things are too deep and private and should not be pried into.”

I found the book’s infrastructure somewhat disappointing. There are source references for most quotations but the unorthodox way the author has chosen to link quotations to their sources is unhelpful. I suspect it also tends to mask the amount of serious research that has gone into the book. More importantly, there is no index. Perhaps the thinking behind these omissions was to enhance the book’s popular appeal by making it look less like a textbook, but they’re a nuisance to anyone who wants to look things up.

Nonetheless, Prof: Alan Turing Decoded is a welcome addition to the literature about Alan Turing: readable, well researched, objective and balanced, and lavishly and professionally illustrated with getting on for a hundred black-and-white images, including previously unpublished family photographs.