The winters at Bletchley Park during the war were ice-cold - the lake was frozen over, the heating was terrible and to cope with the adverse conditions Alan Turing taught himself to knit... and knitted himself a pair of gloves.

"This was typical of Alan - he was very practical," says Dermot Turing, "and not many people know this story. The only thing was he didn't quite know how to sew, so he wore these gloves but the ends of the fingers were open and the wool was just hanging. One of the women at the park felt sorry for him so sewed it up."

When most people think of Alan Turing, they think of the geeky, socially awkward mathematician who played a pivotal role in breaking Enigma - one of the biggest codes that helped the allies win the Second World War. But that merely scratches the surface of what he did, says Dermot.

The nephew of the wartime genius sheds more light on Alan's character and the true story of what he did at Bletchley Park during the war in his latest book, Prof! Alan Turing Decoded.

The 55-year-old from St Albans says: "The book is called Prof as that was Alan's nickname at Bletchley Park. The reason I called it that is to show that there's more to the background of Alan's story.

"There's a danger that when people see the movie (The Imitation Game) they carry around a mental picture which is probably a myth - people think of him as a geek, with no social skills but intellectually a genius.

"But there were questions," Dermot tells me. "Is it true Alan had a rotten childhood? Is it true he committed suicide? I wanted to get to the bottom of those questions. And in most of the cases I was quite surprised by the fact that what I had learnt and what I had believed turned out not to be entirely true."

Dermot attended the same schools and colleges as his Uncle - Sherborne School in Dorset and King’s College in Cambridge. He feels honoured to be have followed in the footsteps of a "great man", despite studying different subjects. He began writing the biography of his famous relative in 2012.

The former lawyer says he had been researching about Bletchley Park and what went on there for almost all his adult life, but it was only on Alan's centenary, after he was asked to do several speeches about him, that Dermot seriously thought about writing it all down.

"His family, like everybody else knew nothing about what he had been working on at Bletchley Park. He hadn't been pushed into the army like most men his age at the time. They wondered why a mathematician would be working for the Foreign Office.

"It wasn't until the mid-70s, when it started to come out what happened at Bletchley Park, but his name only came out in the 1980s and we realised how much of a pivotal role he had."

Comparing it to the film The Imitation Game, in which Benedict Cumberbatch did an "excellent" job of portraying his uncle, Dermot tells me: "In particular what comes out is that there was a struggle and that it took the entire duration of the war to the crack Enigma.

"In fact, Alan was involved in building the machine from 1939 to 1940 - they had it up and running in time for the Battle of Britain in 1940. The scenes were dramatised for the film. This was one of the things that surprised me, how early in the war it was done, that was his major contribution and so what did he do the rest of the time?

"At first he worked on some codebreaking to do with the U-boats. Then, around 1942 to 1943 his role changed - he became the security guard or the game keeper to keep other people from breaking the Allies codes. Part of this job involved him being sent to the US to check out this encryption machine that the British and US wanted to use to communicate with each other.

"He also helped solve the problem of how to encrypt a telephone call."

Dermot says that although there was not much to go on officially - his father, John, who was Alan's older brother, had a file which he had accrued after his death and that proved to be very interesting.

"Growing up my family didn't talk too much about Alan, it was too painful."

Alan was prosecuted for being homosexual in 1952 and was subjected to experimental hormone therapy. He died in 1954 from cyanide poisoning.

"I was born after he died and I know him and my father got on but had very different interests," says Dermot. "My father was the tennis playing type who liked going to parties and having a good time. Alan was much more unconventional - he enjoyed studying and had his group of friends. He actually stayed in touch with everyone he worked with at Bletchley Park throughout his life.

"He was a clever person, who achieved a lot in a short lifetime. My belief is that you shouldn't define Alan Turing by the last few years of his life."

Dermot will be talking about his book and the life of his uncle at the Flamstead Book Festival on Saturday, May 21. Details: