Benedict Cumberbatch has said his latest role as codecracking genius Alan Turing is a world away from Sherlock - despite both characters being "socially awkward" and ultra-bright.

The actor portrays mathematician Turing in The Imitation Game, which tells the story of his prominent role in decrypting coded Nazi messages and hastening the end of the Second World War.

Speaking at the film's launch, Cumberbatch described what attracted him to the role, saying: "I liked how uncompromising he is and that's a strong trait in strong characters, they always have that attraction for me. I've also played stupid people as well - if anyone out there's got some more stupid roles for me, great, bring it on."

He went on: "It's a great honour to be asked to play someone like Alan Turing, so the last thing I want to do is go, 'Well, it's a bit like Sherlock, isn't it'. And it's not, it's really not, and you can't begin to fathom what a character is if you start categorising them as having similarities to other characters.

"I do try to shake it up, but I do see why people think the two characters might have similarities. I understand those comparisons -they're frustrating, yes, but of course I understand them. I too watch stuff."

Asked whether he had tried to minimise the similarities between Sherlock and Turing, Cumberbatch said: "I'm limited by who I am and what I look like, but at the same time they're utterly different people.

"He doesn't swish around in a cloak and curly hair demonstrating how brilliant he is, he's a very quiet, stoic, determined, different hero and I think, yes, he's smart, but the way he has to operate as an outsider and as someone so different is very much out of the conditions of his life.

"As far as the similarity that he's socially awkward, what you see is a whole evolution in him which is humanising. That happens, I suppose, with some aspects of what we do with our version of Sherlock. But no, I didn't read the script and go, 'Oh, this is Sherlock in tweed'."

Cumberbatch was speaking ahead of the European premiere of the film tonight which marks the start of the BFI London Film Festival.

The Imitation Game is set at Bletchley Park, where teams worked around the clock for years to unscramble messages encrypted by the Enigma machines used by German forces.

Keira Knightley also stars in the film as another codebreaker, Joan Clarke.

Turing, regarded as one of the fathers of computing, was given a posthumous royal pardon in December for his conviction for homosexuality - or an act of "gross indecency" - in 1952, which led to his chemical castration and also saw his security clearance being withdrawn for his post-war work at GCHQ. He went on to commit suicide in 1954.

The film's director Morten Tyldum will also be at the screening at the Odeon Leicester Square and there will be simultaneous screenings of the film at cinemas across the UK.

The 58th BFI London Film Festival, in partnership with American Express, runs from October 8 to 19, with Brad Pitt's new Second World War drama Fury bringing down the curtain on the final day.