Second World War code-breaker Alan Turing has been given a posthumous royal pardon for a 61-year-old conviction for homosexual activity.

Dr Turing, who played a pivotal role in breaking the Enigma code, arguably shortening the war by at least two years, was chemically castrated following his conviction in 1952.

His conviction for "gross indecency" led to the removal of his security clearance and meant he was no longer able to work for Government Communications Headquarters (GCHQ) where he had continued to work following his service at Bletchley Park during the war.

Dr Turing, who died aged 41 in 1954 and is often described as the father of modern computing, has been granted a pardon - effective from today - under the Royal Prerogative of Mercy by the Queen following a request from Justice Secretary Chris Grayling.