The brilliant mathematician, who spent his key years at Manchester University, is hailed as one of the founders of modern computing.

But a conviction for homosexuality effectively ended his career. Troubled Turing went on to commit suicide in 1954, aged just 41.

Now a group of admirers of the scientist - named as one of the 100 most important people of the 20th century by Time Magazine - are lobbying the government to make a posthumous apology.

Codebreaker

The Cambridge graduate was one of Britain's best wartime codebreakers - part of the team at Bletchley Park which unravelled the secret of the Enigma code machines used by German U-boats. Turing was awarded an OBE in 1945 for his wartime services to the Foreign Office and moved to Manchester to help work on the pioneering Mark 1 computer.

He was prosecuted for gross indecency for having sex with a man in 1952, but escaped jail after being offered an alternative of taking an experimental hormone treatment to reduce sex drive.

However, the case effectively ended his career and Turing fell into despair. His body was found by a cleaner at his Wilmslow home in 1954 - next to him was a half-eaten apple laced with cyanide. It was not until 1967 that laws against gay men were lifted.

More than 500 people have now signed the petition on the 10 Downing Street website to call for an official apology 'recognize the tragic consequences of prejudice that ended his life and career'.

Hounded

John Graham-Cumming, a leading British computer expert who launched the campaign, said: "I think that Alan Turing hasn't been recognised in Britain for his enormous contribution because he died in his forties and almost certainly because he was gay.

"It is atrocious that we don't recognise this man and the only way to do so is to apologise to him. This man was a national treasure and we hounded him to his death.

http://www.manchestereveningnews.co.uk/news/s/1132035_campaign_to_win_official_apology_for_alan_turing