Alan Turing. (Science Museum, London/SSPL)

“The Imitation Game” was never trying to be just a movie.

The Academy Award-winning biopic about mathematician Alan Turing, considered a hero for breaking the Nazi Enigma Code during World War II but prosecuted under Britain’s anti-sodomy laws, has billed itself as championing gay rights. Even before the film was released, its creators were among those calling for Turing’s conviction to be overturned (he was granted a royal pardon in 2013). In a moving Oscars acceptance speech, screenwriter Graham Moore dedicated his win to “that kid out there who feels like she’s weird, or she’s different, or she doesn’t fit in anywhere.”

Now advocates are hoping to capitalize on that momentum with a petition calling for the government to pardon 49,000 other men convicted under Britain’s anti-sodomy laws.

From Patricia Arquette's booming speech to an emotional performance of "Glory" from the film "Selma," here are the highlights from this year's Oscars. (Nicki DeMarco/The Washington Post)

The petition, which Turing’s relatives delivered to Prime Minister David Cameron on Monday, has been signed by over half a million people. Moore is among them, as are Benedict Cumberbatch, who played Turing in the film, co-star Keira Knightley, director Morten Tyldum and at least nine other cast and crew members.

“Each of these 49,000 men deserves the justice and acknowledgment from the British government that this intolerant law brought not only unwarranted shame, but horrific physical and mental damage and lost years of wrongful imprisonment to these men,” the petition reads.

A second, similar petition from GLAAD has also received more than 500,000 signatures.

Technically, the Queen issues pardons in Britain but only on the advice of the government in power.

The Labouchere Amendment, the law under which Turing and thousands of others were convicted, dates back to 1885. It criminalized “gross indecency” between two men — though, in keeping with Victorian-era prudishness, an exact definition for that term was left to the imagination. The law was used broadly to prosecute thousands of gay men — most sensationally, Oscar Wilde, who was sentenced to two years’ hard labor in 1895. Wilde died in exile three years after his release.

The six decades between Wilde’s and Turing’s convictions did little to change British attitudes toward homosexuality. In 1952, when Turing was brought up on indecency charges, popular thinking called for chemical castration of gay men. According to the Daily Beast, one otherwise socially progressive paper at the time published exposes about the threat of “freaks and rarities” in British society.

“What is needed is a new establishment for them … it should be a clinic rather than a prison, and these men should be sent there and kept there until they are cured,” the paper wrote.

University of Cambridge produced this film in 2012 to mark the centenary of Alan Turing's birth. Turing studied at Cambridge as an undergraduate. (University of Cambridge)

Turing didn’t contest the charges against him and agreed to undergo hormonal treatment that rendered him impotent. The plea kept him out of jail, but he lost his security clearance and was said to have been humiliated by the punishment. Two years later, at age 41, Turing was found dead of apparent suicide. An apple laced with cyanide lay partly eaten by his bed.

Homosexuality was partially decriminalized in Britain in 1967, but thousands of convictions under the Labouchere amendment remained on the books. Even after Turing was pardoned in 2013 — the result of a four-year campaign from scientists and gay rights advocates — Justice Minister Edward Faulks said that the government would not give similar posthumous pardons to other men who were prosecuted. Such a move would strain government resources and have “no practical benefit,” Faulks told the BBC.

That decision sat uncomfortably with many who had advocated for Turing’s pardon.

“I pay tribute to the government for ensuring Alan Turing has a royal pardon at last but I do think it’s very wrong that other men convicted of exactly the same offense are not even being given an apology, let alone a royal pardon,” activist Peter Tatchell told the BBC in 2013.

Tatchell and others kept at the effort, but the issue didn’t gain momentum until “The Imitation Game” was released last year. Matthew Breen, editor of the LGBT magazine the Advocate, started the Change.org petition in late January, just after the Oscars nominations were announced. It has garnered more than 500,000 signatures in four weeks, more than 10 times the number of signatures on the 2009 petition calling for Turing’s pardon.

Cumberbatch has also used his celebrity to champion the issue.

“What we hope to gain is the momentum to use his story to highlight that this was not just an isolated incident,” he said in an interview with Jimmy Kimmel last week. “It’s barbaric, and that was the ’50s, that was less than 100 years ago.”

Turing’s grandniece Rachel Barnes, who is among the group that will be presenting the petition, told the Guardian it was “illogical” for her uncle to be pardoned when so many others were not.

“I feel sure that Alan Turing would have also wanted justice for everybody,” she said.

Despite “The Imitation Game” crew’s advocacy, the film has gotten flak for its portrayal of Turing’s sexuality. The movie doesn’t show any of Turing’s relationships and portrays him as more closeted than he was in real life. (Biographer Andrew Hodges said that Turing was open about his sexuality with friends and colleagues.)

I wish that there had been a vague suggestion that Turing’s sexuality was something other than a burden to him,” Slate LGBT editor June Thomas wrote

But screenwriter Moore said he wasn’t trying to shy away from Turing’s sexuality.

“His whole relationship, how he falls in love and the importance of him being a gay man, was all about secrecy,”  he said in an interview with Variety, “It was not because we were afraid it would offend anybody.”