Peers and scientists including Professor Stephen Hawking are once again pushing for an official pardon for codebreaker Alan Turing.
Turing's death from cyanide poisoning in 1954 was ruled a suicide, coming after his conviction for gross indecency at a time when homosexuality was illegal.
Lib Dem peer Lord Sharkey has already introduced a Private Members' Bill in the House of Lords over the summer to try to get a pardon for Turing, who is credited with helping to end World War II by breaking German encryption at Bletchley Park.
If that bill is passed by both Houses of Parliament, Turing could get an official pardon without consent from the government.
But Lord Grade, Conservative peer, wants the prime minister to use his own authority to pardon Turing. In a written question on Tuesday, he asked the government if they would reconsider their decision not to grant the pardon.
In 2009, then Prime Minister Gordon Brown apologised for Turing's appalling treatment, but he wouldn't formally pardon him for his "crime". A letter to the coalition government also failed to achieve a pardon in February this year.
Justice Minister Lord McNally said this week that the government only handed out pardons in cases where the convicted person could be proved to have been innocent.
"Dr Turing's conviction, essentially for homosexual activity, was the result of an offence which we would now consider discriminatory and which has now been repealed. This was a shocking and inappropriate fate for someone who had contributed so much to science and to the defence of his country," he said in answer to Lord Grade's written question.
"However, it is long-standing government policy that pardons under the Royal Prerogative of Mercy should be reserved for cases where it can be established that the convicted person was innocent of the relevant offence, and not to undo the effects of legislation which we now recognise as wrong."
Lords Grade and Sharkey have signed a letter sent to The Telegraph asking again for the pardon. Professor Stephen Hawking, the Astronomer Royal Lord Rees, Sir Paul Nurse, head of the Royal Society and Baroness Trumpington, who worked for Turing at Bletchley Park during the war, have all co-signed the letter.
The letter urges David Cameron to "formally forgive the iconic British hero".
The peers and scientists may feel they have a better case for Turing now, after the government introduced legislation earlier this year to take the "offence" of homosexuality off people's criminal record if they had previously been convicted of it. ®