World War II was not won by superior numbers, military nous, or even dumb luck. It was won by mathematicians and spies, according to The Imitation Game, the latest film starring Britain’s secret weapon of the acting world, Benedict Cumberbatch. (A man many have described as our generation’s Sir Laurence Olivier.)

We begin, like a lot of careers do, with a job interview. An Alan Turing (Benedict Cumberbatch) aged 27, already a Fellow at Cambridge at 22, gets off to a bad start being interviewed by Commandar Alastair Denniston (Charles Dance). Turing is aloof, arrogant, slightly wet and drippy, immensely intelligent, but with godawful interpersonal skills and a complete lack of a sense of humour.

Denniston takes an instant dislike to him and shows him the door, at which point Turing says ‘Enigma, that’s what you’re working on isn’t it?’ And just when Denniston thinks he has Turing figured out, the tide turns. Much of this is down to Cumberbatch. He’s 38 years old and getting better with every role he takes. This could well be his best, most nuanced, complex and satisfying performance (in film) so far.

To return to the plot a moment, with the Nazis winning the war and their Enigma-encrypted messages making the Allies’ job of stopping them particularly difficult, Denniston puts together a team of codebreakers and mathematicians, with the help of the Chief of MI6, Sir Stewart Menzies (Mark Strong).

The team is led by chess champion, the sauve and debonair Hugh Alexander (Matthew Goode) who, like seemingly everyone else, takes an instant dislike to Turing, his inclusion in the team, and the fact he refuses to work with the rest of them, spending his time tinkering with his designs for his own machine to beat Enigma.

Realising he won’t get anywhere with these tactics, Turing goes above Denniston’s head to Winston Churchill, who promptly puts him in charge of the whole team and provides him ample funding to build his machine. Turing then fires half the team and recruits new talent, including brainiac Joan Clarke (Keira Knightley), with whom he begins to form a close bond as they work together.

Directed by Norwegian director Morten Tyldum (who directed the excellent Headhunters in 2011), this film jumps around in time, giving us glimpses of Turing’s childhood, and his life after the war, including issues around his sexuality. Whilst the time skips can come thick and fast on occasion, they are never jarring, and help build up a succinct picture of Turing and how his drive and focus to achieve great things ultimately led to him cracking Enigma.

We also get to see his human side, as the film devotes a significant amount of time to his relationship with Joan, and how she helps him bond with his colleagues. In this respect great credit should go to Knightley. She often plays strong, glamorous parts. Here she uses her inherent geekiness to good effect, making Joan seem likeable, accessible and caring, particularly when it comes to dealing with an erratic Turing.

I’ve read that DiCaprio was originally attached to play the lead role. I just cannot see how that would have worked. Granted he’s a fine actor (and he’s already played oddball Howard Hughes, so he’s got form), but he’s just a bit too handsome and, well… American. It had to be a British actor playing this role surely?

And Cumberbatch’s performance will be talked about for a long time to come. He thoroughly inhabits the character of Turing. Stammering, stuttering, hanging his head, lowering his eyes, letting his lower lip form a weak mouth, his physical performance was engrossing from start to finish.

Surely the sort that should have Oscar written all over it?

All in all, for a film which largely involves writing equations on a blackboard and scribbling on little bits of paper – basically maths – it is tense, exciting, well paced and packed with fine performances, including a truly special one from Cumberbatch. It charts an important part of British (and modern) history and, even if you’re not an card-carrying member of the Cumberbitches, this should be on your ‘to watch’ list in the near future.