Whoever heard of interview by crossword puzzle? Well, that’s how Alan Turing insisted that his team was selected for the job of cracking the Enigma Code.

Poor old Turing. Arguably he was as big a hero as any of the military commanders in winning the war, but until recently his role has been diminished and overlooked due to his persecution for homosexuality, which led to his suicide. We have all heard of the Enigma Code, indeed many of us have read or seen versions of the story of the magic code-breakers, based at Bletchley Park, whose work  solved the puzzle of German military and naval signals, changing the course of the war.

This is a thoroughly enjoyable drama, despite the purists arguing that many of the details are wrong – not least the name of Turing’s beloved computer, here ‘Christopher’ in honour of his dead school friend, and certainly not the treasonable offence of shielding a spy in return for keeping silent on his sexual orientation. 

It flits between the three main phases of Turing’s life, from his days as a bullied and autistic schoolboy, to his work at Bletchley and then to his arrest and interrogation in the early 1950s (the director even gets the date of that wrong too – sorry, carping again).  The character of Turing remains central throughout each of these periods. Alex Lawther is the perfect young Alan – geeky, nerdy and, according to his mother, ‘an odd fish’. He even looks like Cumberbatch. Good casting. For once this time travel works well.

At school we see his boffin-like character emerging, along with the awakenings of his first love for his older school-friend, who introduces him to coding; at Bletchley we meet the arrogant and impossible genius who, like all autistic people has no notion of tact or empathy – there is a an amusing scene where he has been advised that to lead his team he must make them like him, so he buys them apples and tells a very tired joke; and, finally, shamed by rampant homophobia, we see his despair at having to choose chemical castration over prison and the resulting terrible physical  and mental effects. 

It is an indictment on the narrow-mindedness of society and a reminder that Turing was only granted a pardon in 2013 – although, again, this is controversial, as many people so-charged refused to apply for pardons on a matter of principle: there was no crime. In Turing’s case, perhaps, it has allowed him finally to gain the recognition he so deserves. 

Benedict Cumberbatch is a shoe-in for Turing. He has the rather other-worldly charming good looks which suit the character, imbues it with a bit of Sherlock and all of his skill: the mannerisms of a genius that ensure he alienates his boss, Commander Denniston, played by a flinty Charles Dance, and the code-breaking team he joins at Bletchley, led by Hugh Alexander (Matthew Goode), an attractive, louche natural leader of men (and women) and a good counter to Cumberbatch’s Turing. 

Keira Knightly excels in the role of Cambridge double-first Joan, who joins the team out of frustration at the misogyny shown towards her academic career (it’s not just men who suffer, you know). A perfect foil to Turing, she acts as his protector and is the glue that binds the team, even becoming engaged to him for a while, as she did in ‘real life’. It is one of the first times that I have not found her to be type-cast and irritating.

Director Tyldum, whose other credits include the thriller Headhunter,injects a little of that genre into his film: the tension over whether Turing’s computer will work, the sense of time running out, the difficult team dynamics and even Alan sneaking into Joan’s room to discuss mathematics. All give the film a thread of drama that holds the flitting to and fro together.

The Imitation Gamefeels like a bit like a BBC Period Drama – strange for a Norwegian director – but it is no worse for that, with its scattering of familiar faces such as Mark Strong as the MI6 man, and Rory Kinnear as the policeman. I was rather taken by the war-in-action scenes – and the newscast sequences – as my mother was Wren and a cypher officer during the war, and it gave me an image of what it must have been like working in a nerve centre of planning: scores of women (and men in her case) clack-clacking on their machines.So, another heavyweight movie in contention for the Oscars, sharing nine nominations with Birdman, compared to only five for The Theory of Everything. My money remains firmly on Eddie for Best Actor and Birdmanfor Best Movie. Maybe Keira will get lucky with Best Supporting. Time will tell…