Dermot Turing is showing me a flower. “Take a look at this daisy,” he says, spinning the flower in his hands, the sole decoration on the table of the comfortably shabby Indian we’re meeting in. “If you look at the centre, you’ll see the patterns are arranged in spirals. One way, they spiral clockwise. The other, anti-clockwise. And they’re typically adjacent numbers in the Fibonacci sequence. Why? We don’t know.”
Alan Turing, the mathematician and codebreaker, was wrestling with exactly this problem when he died in 1952, his paper on the formation of daisy petals half-finished. Yet it is for his advances in morphology – the maths which underpins the natural world – that Dermot believes his uncle should be best known.
“Alan wasn’t a particularly good codebreaker,” he says with a grin. “He didn’t do it for very long and at Bletchley Park he solved the Enigma problem presented to him in about three months, then moved on. So what he’s famous for, he shouldn’t be known for at all.”
Dermot is the son of John, Alan Turing’s older brother. Like his father, he pursued a career in law. But like his uncle, his first love was science and he took a doctorate in genetics at Oxford. He never met Alan, though, who died, apparently by suicide, seven years before he was born.
“There was no family lore about him. My father knew he had been involved in computing, and worked at Bletchley Park, but prior to the declassification of documents in the 70s and 80s, no one knew anything.”
It was Benedict Cumberbatch’s turn as his uncle in the 2014 film, The Imitation Game, which kick-started public interest. “That was what made them stick him on the 50 quid note and name ring roads after him. Before then, no one could even spell my name!”
Turing has a warmly exasperated relationship with Morten Tyldum’s blockbuster. It is, after all, why he has a busy second career as Turing’s closest living relative – he’s due to dash off to speak at a cybersecurity conference after our lunch.
But he scoffs at its inaccuracies: “This idea that the Second World War was single-handedly won by Benedict Cumberbatch sitting in a shed in Bletchley Park being an unobjectionable so-and-so has become definitive,” he sighs. “As for the notion that he spent his final years as this abject creature pining for his dead boyfriend. Well, I won’t use the word but it begins with bull–...”
Instead, Turing sees his role as adding nuance to his uncle’s mythology. He published a 2015 biography of Alan as well as several accounts of Bletchley Park and Second World War code breaking.
His latest book, though, is perhaps his most incendiary. Called Enigma Traitors, it peers into the shadowy flipside of the usual triumphant Bletchley Park story: the murk of code-making and cybersecurity. Neither the Germans, nor the British, come out of it well. The Germans were reluctant to accept that their Enigma machines – at the time, the world’s foremost code-making devices – had been compromised. The British, for their part, were complacent, believing that their early superiority in cracking Enigma meant they didn’t have to update their own codes.
“We have a 2-D picture of code-breaking,” Turing explains. “Bletchley Park, Alan Turing, our skill in cracking Enigma – they all blind us to the fact our codes were cr–p and minimise the work of our Allies, especially the Poles, who brought us the Enigma codes in 1939 at huge personal cost.”
In fact, Enigma Traitor’s twin themes are the institutional inertia of British and German high command – and the awful costs of their unwillingness to confront their failures.
“It’s quite horrible to think about the consequences of the two-year delay in facing up to the [compromised codes] by the British Navy,” he says. “The number of merchant seamen who lost their lives, the thousands of tons of shipping going down. It was the nastiest part of the battle of the Atlantic. That seems to me to be an appalling consequence.”
Was British arrogance to blame? He considers: “There was a prevailing culture of amateurism. We tend to think of Bletchley Park with hindsight as this super intelligence factory. But at the beginning of the war, it was effectively a cottage industry, employing 200 people, held together with sticky tape and string.”
His book ends with a warning for today’s cyber experts. “It’s not my mission to say GCHQ is doing a terrible job now, because frankly, I’m not qualified to speak on that. But I do hope those with decision-making powers are thinking about this stuff because we ignore the lessons of history at our peril.”
He continues: “I suspect if there was another big conflict like the Second World War, we’d find ourselves underprepared.”
What holds us back, he says, is a misplaced nostalgia for the achievements of the past. It was perhaps this nostalgia which led Rishi Sunak to choose Bletchley Park as a venue to host his much-touted global AI summit next week. Alan Turing, of course, is often called the “godfather of AI” for his work on machine consciousness. Most famously, he posited the “Turing test”: a thought experiment about whether a machine could pass as a human. What would he make of Sunak’s summit?
“I suspect he would have been laughing behind his hand at it,” Turing says. “He wrote about machine learning in the 1940s and the danger of robots taking our jobs. He would be appalled that the debate hasn’t moved on in 80 years.”
Bletchley Park looms large in the “sepia-tinted” narrative of the Second World War. “There’s a danger in overblowing its importance, and especially focusing on a few key individuals,” Turing argues. “Nasty, complicated conflicts aren’t solely won by people pushing bits of paper around in draughty sheds, eating bad food.”
He’s both pleased and frustrated that his uncle has come to stand for a six-year operation which, at its height, employed a staff of thousands. “Other guys at Bletchley Park did just as significant work. But Alan’s adulation is all tied up in his personal fate.”
After the war, in the early 1950s, Alan Turing was living in Manchester. A gay man who had never hidden his sexuality, he became involved with an unemployed 19-year-old called Arnold Murray. Soon after, his house was burgled. Turing, convinced Murray was to blame, reported it to the police and confessed their affair.
Both men were convicted of gross indecency and Turing accepted a course of libido-suppressing drugs in lieu of imprisonment; they made him impotent. Two years later, Turing was found dead, poisoned by cyanide. An apple was found near his body and, though it wasn’t tested for the poison, it was speculated that this was how he had killed himself. The coroner ruled suicide.
It’s the best-known episode of Turing’s life, inspiring Steve Jobs to choose a half-eaten apple for his company’s titular logo. But it’s the part which Dermot finds most difficult to discuss.
A few years ago, he published explosive extracts from a memoir by his father. “I will not go to the lengths of pretending I like homosexuals,” John Turing wrote in the previously unseen account. “To my mind, what is intolerable is the world of the ‘gay crusade.’”
After expressing his distaste for the “great deal of rubbish which has been written about Alan”, he concludes, movingly: “Had he been better understood when he was young – and if I, among others, had treated him with more consideration – he might be alive today.”
Why publish it? “It was essentially an attempt to set the record straight,” Turing says. “[My father] was very troubled by Alan’s conviction and the possible relationship between his conviction and suicide. He felt guilty because he had fallen out with him at that point – and he felt very ashamed.”
What does he make of his father’s apparent bigotry? He considers: “My father was born in the Edwardian era, and in the 1950s, the prevailing view was homosexuality was a bit disgusting. Now we have rainbow flags flying everywhere, but in those days, that was not an acceptable social attitude.”
Turing’s death has been much picked over. Some speculate Turing had poisoned himself accidentally, absent-mindedly eating the apple after tinkering with dangerous chemicals.
Dermot doesn’t buy it: “He definitely died by his own hand. All other theories are basically unsustainable. The question then becomes, why? Alan had intended to leave the planet at a time and a manner of his choosing. People still find that deeply uncomfortable as a concept. My speculation is it was boyfriend trouble, but I don’t know.”
In 2009, Gordon Brown issued an official public apology for Turing’s conviction. And in 2013, Queen Elizabeth II granted a posthumous pardon. Turing has become an LGBT icon: a symbol of non-conformity, crushed by a brutal state. Yet Dermot thinks the obsessive focus on the final years of his life is “distasteful”. “We love the Shakespearean arc of his life. It’s a one-man version of Hamlet.”
Rather, he hopes the extraordinary diversity of his uncle’s genius will become better understood. That he’ll be known for his code breaking at Bletchley Park, but also his pioneering theories of computing – and, yes, his quest to understand the mathematics behind the delicate beauty of a daisy.
“Let’s celebrate my uncle for his life, not just his death,” he says.
Enigma Traitors is published on Nov 2. Order from the Telegraph bookshop