Do you worry, too, when at the beginning of a film, you read ‘Based on a true story’? Just how far off the base are we going to fly, Brother? At a fairly great altitude in The Imitation Game. It is a great story. A man named Alan Turing had not been all that brilliant at his public school or at King’s College Cambridge, but he had mind of unexampled power when it came to solving puzzles and inventing machines to solve them. This extraordinary gift was truly providential for mankind in helping England to defeat Hitler. But Turing was homosexual and he got caught after the war. Rather than face prison, he agreed to hormonal treatment to take away his predilection. A couple of years later, he took his own life. A man who might fairly be said to have saved the nation was chemically castrated. After the laws changed and the work of the decoders became known, the English Prime Minister, Gordon Brown, gave an apology in Parliament. The Queen has since granted a pardon. It is hard to believe that these events happened in my lifetime.

This story is told lovingly by Andrew Hodges in Alan Turing: The Enigma, but it runs beyond 700 pages and it has a lot of technical stuff.  I learned that Turing’s father got him exempted from cricket at school and allowed to play golf. This may not have helped. The film shows Turing as a kind idiot savant who will not team with anyone. His mother enforced caste – Alan was not to play with children of a plumber for fear his accent might suffer. This would not have helped either. Nevertheless, Turing survived all this, and Princeton, and went on to become the leading figure at the now famous Bletchley Park in decoding.

The German Enigma code was driven by a fiendish machine and was regarded as unbreakable. Turing broke it. He did so by making a machine that prefigures the computer that will convey this note. It was a colossal achievement, and one that undoubtedly shortened the war and saved lives – fourteen million according to the film. The delicate part lay in how to use decoded material without alerting the enemy to the fact that the code was broken.

This is a wonderful example of how the English harnessed all their very best minds to fight the War – by expelling or killing Jews, Germany tended in the opposite direction. But the producers of the film have not been content with this story which so deserves to be told. They had to dress it up, or sex it up, with quite unbelievable espionage extras and moral dilemnas and conflict with the military that is overdone. After you wonder whether this is 007 or the Famous Five, you are left with a lot of soap and too many typed caricatures. The film is at risk of collapsing in smarmy silliness. You will still get the basis of the story, but I cannot help thinking that the subject could have ruefully foreseen the trimmings. He deserves better. He was a most remarkable man, and the whole world is in debt to him.