Benedict Cumberbatch's Imitation Game: Who was the real Alan Turing?

The Imitation Game opens in the UK today, starring Benedict Cumberbatch and telling the story of Alan Turing, the famed Bletchley Park codebreaker.

It portrays the conflicts and human dramas at the heart of the great effort to crack the German Enigma code during World War II. It is gritty, realistic and often grim. Turing's tortured persona is at the heart of the film, as he himself was at the heart of Bletchley Park.

However, the enterprise involved far more than one man. At its peak in 1945, some 9,000 people worked at Bletchley, 80 per cent of them women.

One of them was Mair Russell-Jones. She died on December 28 last year aged 96, on the day her extraordinary story was published. Written by her son Gethin, a Baptist minister, much of My Secret Life in Hut Six is in her own voice, transcribed during long conversations in the last years of her life.

She had vivid memories of Turing, of whom she was "in awe". Regarded as the father of modern computer science, he was homosexual at a time when it was still illegal, endured chemical castration and committed suicide in 1951.

Mair said: "He was treated terribly by the government after the war and by the nation in general. This man was a hero and he died in awful loneliness. This brilliant man should have been honoured, not made to feel unwanted."

In the film, Cumberbatch portrays him as a mathematical genius who found it hard to relate to other people and was obsessed by the desperate need to solve the Enigma code and win the war. Mair remembers some of his eccentric behaviour: "He was obsessed with keeping fit. I saw him a few times, jogging and running. One of my strangest memories is of him cycling around the grounds wearing a gas mask. I never discovered why he did it, but I'm sure he had his reasons."

Cumberbatch's depiction of his awkwardness around people, too, would have rung true. "He was a very shy man," Mair said. "I spoke to him a few times, mostly in the canteen. He was very polite, but always seemed distracted, as though he was thinking about something else. I wouldn't say he was a happy man, but he was always courteous. I think he had a bit of a speech impediment which probably heightened his loneliness.

"Some of the girls told me they'd seen him wearing pyjama bottoms in working hours. I never saw that but I could believe it. There were other strange rumours. Some said he chained his tea mug to the radiator in Hut Eight whereas others said he deliberately fixed his bicycle chain so that it would come off at various intervals unless he counted the revolutions. He was every inch an absent-minded professor with his head in the clouds."

Among the breakthroughs in the Enigma project was the hazardous recovery of a machine from the German U-boat U-559, sunk in the Mediterranean in 1942 by HMS Hero; two of the three men who boarded her in search of the machine drowned.

Right to the end of the war, the Germans never knew that the Enigma code was broken and that their secret messages were being intercepted. Bletchley Park's codebreakers are reckoned to have shortened the war by two years and saved countless lives.

Mair Russell-Jones was in some ways an unlikely contributor to the war effort. Born in 1917 in Pontycymer in South Wales, she had spent two years at the Mount Hermon missionary training college in London, working among Jewish refugees in the East End. Among other experiences, she recalled the Battle of Cable Street with Oswald Mosley's Fascists, which helped convince her of the need to stand up to the Nazis – against the convictions of the man she was to marry, John Russell-Jones, who remained a convinced pacifist all his life.

She went on to study Music, History and German at Cardiff University. In 1938 a strange encounter changed the course of her life. One quiet afternoon in the library, a man tapped her on the shoulder and told her he was from the Foreign Office – "He said he'd heard I was very good with languages and puzzles, and would I like to try out for a top secret project?"

Mair thought it sounded "important, serious, and, if I'm being honest, a little bit glamorous". She applied and was invited to interview in London, where the full extent of the secrecy around her role became clear when she was asked to sign the Official Secrets Act. She was told to keep details of her work secret for the rest of her life, even from her husband and family.

Mair began work at Bletchley Park in August 1941, working eight-hour shifts through the day and night with a 30-minute meal break. The work was carried out in silence, often under pressure, and could be "numbingly tedious". Yet, she writes, "It was a marvellous atmosphere in many ways because you weren't aware of class or background. We were there to do a job and that's all that mattered... even though we had to keep so many secrets and work the longest hours, there was something about that community at Bletchley Park that I haven't seen since."

The respiratory problems in the huts eventually led to Mair catching pneumonia in late 1944 and going into hospital until March 1945 – two months before Germany surrendered.

In 1998, her son Gethin was looking through a book about Bletchley Park and recognised his mother in a photograph. However, it was only in 2008, when she received a certificate, official government citation and commemorative brooch from Prime Minister Gordon Brown, that she felt free to talk about her experiences. Her memories of the work she did, the people involved, the hardships and tragedies of the wartime years, were still vivid.

Gethin told Christian Today that writing the book about her experiences had been an "immersive" experience. "I wanted to see the world through my mother's eyes as it was when she was in her 20s, and that was very odd.

"It was a compelling, strange experience."

Reflecting on her commitment to the struggle against fascism and his father's pacifism, he says: "It was a very interesting relationship. If they ever had disagreements, it never spilled over into their family life. As far as he was concerned, his stance as a conscientious objector was the only Christian one, and my mother said nothing – though she was directly involved in the war.

"He was very proud of her."

Her Christian faith sustained her during difficult times there, when she sometimes felt out of place in what Gethin describes as "quite a bohemian group – though the work was so tedious and endless that a lot of the bohemianism was drained out of people".

However, he says: "When I pieced together the story of her life, she came out as resilient, feisty and a natural leader. There was a doggedness about her that got her through."

He recalls her says that Turing was "the most brilliant man she ever knew". "She was very loyal to him and felt he was treated abysmally. She'd be delighted by the film. She was very proud to be associated with his name."

However, Mair recalled, "During the years I worked there I never cracked a single code; if I did, no one ever told me."

Despite the frustrations and difficult working conditions, she looked back on her time at Bletchley Park with pride and fondness.

"The four years I spent working at Bletchley Park were among my happiest but I have spent most of my life trying to forget everything about it. I've given up on that now, enjoying the knowledge that I was part of one of the most exciting teams that ever represented Britain. It was drummed into us at the time that everything we did there was secret, and when the war ended we were advised to forget everything. So I deliberately tried to mentally burn all my memories of that period. I blotted out feelings, events and people from that time. But as others have told their stories of life in Bletchley Park, I realised that I could tell my own.

"It's strange that even though so much has happened to me since leaving Bletchley Park, those four years have probably influenced me more than the other 92."

My Secret Life in Hut Six is published by Lion, price £9.99.