Mathematician Turing led a team at Bletchley Park country House north of London which cracked the Nazis' Enigma code - regarded by the Germans as unbreakable - a move credited with helping to shorten the war and save countless lives.

However, five years after the war he was convicted of gross indecency under laws which banned homosexuality and was sentenced to chemical castration involving a series of injections of female hormones.

The conviction meant Alan Turing, a pioneer of modern computing, losing his security clearance and being unable to continue his work. In 1954 he killed himself at the age of 41.

The legislation used against the maths genius was the same as that used to prosecute and jail playwright Oscar Wilde in 1895 during a Victorian clampdown on homosexuality and it was only repealed in 2003.

In 2009 British Prime Minister Gordon Brown apologised for the treatment meted to Alan Turing.

It was at the National Museum of Computing at Bletchley Park that Turing and fellow scientists designed and developed Colossus, a truck-sized machine which was one of the world's first programmable electronic computers.

However the work was not widely known beyond academic circles as Britain kept their role in the war secret.

Then Prime Minister Winston Churchill ordered that the Colossus computers and 200 so-called Bombe machines, used to crack the Enigma code, be destroyed to keep them secret from the Soviet Union. Bletchley's existence only came to light in the 1970s when the veil of secrecy was lifted.