Alan Turing, the second world war codebreaker who took his own life after undergoing chemical castration following a conviction for homosexual activity, has been granted a posthumous royal pardon 59 years after his death.

The brilliant mathematician, who played a major role in breaking the Enigma code – which arguably shortened the war by at least two years – has been granted a pardon under the Royal Prerogative of Mercy by the Queen, following a request from the justice secretary, Chris Grayling.

Turing was considered to be the father of modern computer science and was most famous for his work in helping to create the "bombe" that cracked messages enciphered with the German Enigma machines. He was convicted of gross indecency in 1952 after admitting a sexual relationship with a man.