We went to see The Imitation game last night. It’s a well-made, entertaining travesty, distinguished by a terrific performance by Benedict Cumberbatch as somebody’s weird idea of Alan Turing, and marred by a few howlers — some malicious (like the idea that Turing was suspected of being a Soviet spy both in Bletchley Park and afterwards in Manchester), some merely absurd (like the idea that he christened the first Bombe ‘Christopher’ after the dead boy he idolised when they were at school in Sherborne), and some completely implausible (like the scenes in which the codebreakers have a map of the north Atlantic with paper markers setting out the positions of ships in a convoy).

Cumberbatch is clearly a great actor, and his performance is memorable. But the unsubtle, autistic Turing he portrays is substantially at odds with the Turing who, for example, was entrusted by the British government with the task of hoodwinking the American codebreaking community into thinking that the British were way behind them in breaking German ciphers.

What the film does convey powerfully, though, is the cruelty of Britain’s homophobic laws. Walking home afterwards, I was reminded of the courage of the MP Leo Abse and the hereditary peer Lord Arran, the first Parliamentarians to publicly accept the recommendations of the Wolfenden Report, and of Roy Jenkins, the only liberal (small-l) Home Secretary in living memory, who ensured that the Sexual Offences Act 1967 made it onto the statute book.

Ironically, we saw the film the day after the Chancellor, George Osborne, announced that the £42m Turing Centre would be located at the British Library next to King’s Cross.