He was one of the greatest minds of modern time, a founding father of computer science, and his legendary breaking of the Enigma Code may have been a tipping point in the struggle against Nazism. Few men have contributed so much to human learning or to his country's survival. But Turing was persecuted into suicide by the homophobia of his time and barred from entering the US because he was a homosexual (now America reserves that distinction to homosexuals with HIV). Here is the story of his death:

In January 1952 Turing picked up the 19-year-old Arnold Murray outside a cinema in Manchester. After a lunch date, Turing invited Murray to spend the weekend with him at his house, an invitation which Murray accepted although he did not show up. The pair met again in Manchester the following Monday, when Murray agreed to accompany Turing to the latter's house. A few weeks later Murray visited Turing's house again, and apparently spent the night there.

After Murray helped an accomplice to break into his house, Turing reported the crime to the police. During the investigation Turing acknowledged a sexual relationship with Murray. Homosexual acts were illegal in the United Kingdom at that time, and so both were charged with gross indecency under Section 11 of the Criminal Law Amendment Act 1885, the same crime that Oscar Wilde had been convicted of more than fifty years earlier.

Turing was given a choice between imprisonment or probation conditional on his agreement to undergo hormonal treatment designed to reduce libido. He accepted chemical castration via oestrogen hormone injections which lasted for a year. One of the known side effects of these hormone injections was the development of breasts, known as gynecomastia, something which plagued Turing for the rest of his life. Turing's conviction led to the removal of his security clearance, and barred him from continuing with his cryptographic consultancy for GCHQ.

Every now and again, we should remember how brutal the persecution of homosexuals was for so long, how counter-productive, how many lives were ruined, and how a great man like Turing could be reduced to suicide by the oppression he lived with on a daily basis. And so it is a good thing that Britain has now offered a formal apology to Turing - if fifty years too late. Here are prime minister Brown's words.

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