The Duke and Duchess of Cambridge William and Kate have declined to back a campaign to pardon at least 49,000 gay men who were convicted of gay sex convictions.

The campaign, which is backed by Stephen Fry and Benedict Cumberbatch, estimates that at least 49,000 men were convicted under gross indecency laws.

An open letter signed by Fry and Cumberbatch, asked Kate and William to join the campaign.

Cumberbatch played Alan Turing, the gay codebreaker and computer genius in ‘The Imitation Game’. Turing was convicted of gross indecency and chemically castrated. He later killed himself.

The letter, addressed to the Government, was published in the Guardian.

It reads: “The UK’s homophobic laws made the lives of generations of gay and bisexual men intolerable.

“It is up to young leaders of today including the Duke and Duchess of Cambridge to acknowledge this mark on our history and not allow it to stand.

“We call upon Her Majesty’s Government to begin a discussion about the possibility of a pardoning all the men, alive or deceased, who like Alan Turing, were convicted.”

However, a spokesman for the Duke and Duchess of Cambridge said as this is a matter for the British Government, the couple would not comment on this issue publicly.

An apology for Alan Turing was issued by then Prime Minister Gordon Brown in 2009, and the Queen in 2013 granted a posthumous pardon under the Royal Prerogative of Mercy.

Campaigners argue that all men who were convicted should be granted a pardon.

The letter continues: “The apology and pardon of Alan Turing are to be welcomed but ignores over 49,000 men who were convicted under the same law, many of whom took their own lives.

“An estimated 15,000 men are believed to still be alive.”

Peter Tatchell, who supports the campaign, told PinkNews: “An estimated 50,000-100,000 men were convicted under Britain’s anti-gay laws during the twentieth century. All these men deserve a pardon, like the one that was granted to Alan Turing. His pardon was much deserved but he should not be singled out for special treatment. Unfairly, no such pardon has been extended to the tens of thousands of other gay victims – not even to other high profile victims such as Lord Montague and Sir John Gielgud.”