Leaning over the desk at Bletchley Park where his uncle Alan Turing cracked the German codes that helped win World War Two, there is an almost childlike excitement on Sir Dermot Turing’s face.

Because for him his famous relation’s life is about so much more than how it tragically ended in suicide – and he is determined to help keep the Codebreaker’s legacy alive.

“While I don’t ever try and get away from the Shakespearian tragedy of his life,“ says the St Albans solicitor, “I think it’s quite important not to let that aspect of it become the story of his life.

“The questions he asked such as ’do computers think?’ are still relevant today and so much more important than the question of what happened in the end,“ he says as we stroll pass the Bombe machine that Turing invented to crack the Enigma codes.

“Also he didn’t work on his own here and single-handedly win the war for the Allies,“ says Dermot. “He was part of a bigger team of thousands of people who together did an amazing thing.“

Much of Turing’s remaining family live in St Albans and Dermot has been a trustee of the heritage site since 2012 and will be there today (Wednesday) to see the Duchess of Cambridge unveil a £8million restoration. It has seen derelict buildings saved from crumbling to dust and the landscape return to its 1940’s appearance.

Dermot says: “The first question I asked when I was discussing being a trustee was ’how do we keep it for the younger generation and not just preserve old buildings?’ We want it to be more than that.“

Block C has been transformed into a visitors’ centre with interactive exhibitions letting visitors have a go at codebreaking, Huts 3 and 6 have been carefully restored and a car park outside the main mansion has been removed and the area restored to lawn, as it would have been during the war, with recorded sounds of snatched conversations and tennis games helping people step back in time to Turing’s era.

His work at Bletchley will also be brought back to life on the silver screen this autumn in The Imitation Game, which was partly filmed at the park with Dermot’s son James playing an extra and getting to meet star Benedict Cumberbatch who stars as Turing.

“It will be fun, as long as people don’t treat it as a documentary. It is a work of fiction and liberties have been taken, “ says Dermot.

His uncle’s life is in the limelight this year as not only is it 60 years since his death, but in December the Queen granted him a royal pardon for his conviction which Dermot thinks was ’controversial’.

“There were many people who were subjected to that same kind of thing and I think it’s odd that one person gets singled out for a pardon just because he happens to be famous. I suspect many people might feel bitter about that and I would sympathise with that.“

While Turing’s family guessed what he was involved in during the war, like everyone else they only found out the truth about what went on at Bletchley Park in the mid-’70s.

As a result the site, near Milton Keynes, was never maintained and in 1991 was nearly bulldozed, but was saved when the local council declared most of it a conservation area, and the Bletchley Park Trust was formed to maintain it as a museum, which opened in 1993.

Dermot says it was only then that people began to learn about his uncle, adding: “The founding of Bletchley and the fame of Alan Turing go hand-in- hand.“

Even now much of Bletchley’s history remains secret as it is still classified or locked away in the minds of the people who worked there.

“Some people are still very reluctant to talk about what they did because they signed the Official Secrets Act and for them that meant it was something they should never reveal,“ says Dermot.

But he has been lucky enough to meet some of the “very bright bunch” who worked alongside his uncle and says: “When it came to the social side he was pretty awkward. He’s quite easy to characterise as a mad professor, but people he worked with say he was very kind, generous, amusing and loved children.“

The question of whether his uncle intentionally committed suicide, two years after being convicted of homosexuality and being chemically castrated, is still “very difficult to answer”, but Dermot says his father John was persuaded that is what happened and adds: “I don’t think we need to look very far in Alan’s life to find a reason for suicide and that’s enough for me.“

Details: bletchleypark.org.uk