Dir:

Morten Tyldum

With: Benedict Cumberbatch, Keira Knightley, Matthew Goode

Runtime: 114 minutes

SUCH is the wealth of cut-glass accents in Morten Tyldum's drama about Alan Turing and his Bletchley Park team, a more fitting title might be Five Go Code Breaking, or Brief Encounter with Added Tweed. The Imitation Game is a terribly pukka piece, perhaps too bone china for its own good at times, but it is also a rattling good yarn expertly played by a best of British and Irish cast, and one directed, moreover, by a Norwegian. If you warm to tales of wartime endeavour, of spies and lies and the twisted workings of the British Establishment, then pull up a cinema seat for an object lesson in how 2001's Enigma should have turned out but, woefully, did not.

We first meet Turing, played by Benedict Cumberbatch, in 1951 in a police interview room. The war is now a distant but still distinct rumble in the past. Turing's efforts in cracking the Nazi's Enigma operations code, and saving countless Allied lives, have not been forgotten by the great British public because they were never known about in the first place. The work at Bletchley Park was top secret, so to the detective given the case, Turing is just another burglary victim, albeit one who does not wish the matter investigated. The policeman senses something amiss and determines to dig deeper.

At a flash - the pace at which Tyldum, the director of the acclaimed Scandi thriller Headhunters does everything in his films - we are back in 1939 and Turing the mathematician is being interviewed again, this time for a position at Bletchley Park. With more than a hint of Sherlock, Cumberbatch joins some more dots in his character. Ferociously clever (a fellow at Cambridge at 24), arrogant, aloof, Turing tells the uniform in front of him that he likes solving problems and that Enigma, being the most difficult problem in the world, will be the ultimate challenge.

The men from the Ministry of War take him on reluctantly, assemble a team around him (including Matthew Goode as Hugh Alexander and Allen Leech as Lesmahagow-born John Cairncross), and even more reluctantly spend a vast amount on a machine which Turing promises will crack the code. Meanwhile, the equally brilliant Joan Clarke (Keira Knightley) has arrived at Bletchley. Being a woman of her time, however, Clarke is confined to a support role.

Tyldum, working from a screenplay by Graham Moore from the book by Andrew Hodges, expertly calibrates the race to crack the code, mining excitement and drama from the process. Crucially, he finds the humour in adversity, too. The ever brilliant Mark Strong, playing a shadowy (what else) intelligence chief, wields lines so delightfully dry they could have arrived at Bletchley via the Gobi Desert.

Boosting the polished air is a superb production design, with all the vintage bikes, trilby hats, chintz furniture and classic cars one's heart could desire from a period piece.

As the team's efforts continue to come to nought, the pressure builds on Turing to make good on his promises. Every day lost equals more lives lost.

From his struggles with the code, and the flashes forward to the 1950s, we learn more about Turing the man, though here the film becomes rather coy. Turing's homosexuality is tiptoed around as though it was almost an incidental part of his character. He was a genius, undoubtedly. He was a hero, certainly. But he was a gay man as well, and it was because of this that he was so cruelly treated after the war. While the film touches on all these points, it could have done so more forcefully.

The film's title comes from an experiment devised by Turing. In the test, questions are asked of a machine and a human, with the questioner having to decide if the respondent is a human or otherwise.

There is no such confusion as to where Tyldum's picture is coming from. This is a long overdue, thoroughly heartfelt and thrillingly executed salute to a true British hero.