Is the British Prime Minister being blackmailed by one of the world’s top media magnates? That’s the astonishing claim being made by a former tabloid reporter. “What else do you think that secret meeting over Christmas between Rupert Murdoch’s people and Cameron was about? And why else do you think that Murdoch himself has turned up in London now?” asks former News of The World reporter Harry Spanks. “I’ll bloody tell you why – they’re threatening the Prime Minister that, if he doesn’t guarantee that News Corp’s buy-out of Sky TV is allowed, they’ll release that porn movie he unwisely appeared in when he was a student!” According to Spanks – who was fired from his job at the Sunday tabloid after he was implicated in the illegal phone-tapping scandal – the media baron secretly obtained the film several years ago, when Cameron first became leader of the Conservative Party. “He was thinking ahead – he knew it was only a matter of time before Cameron got to Downing Street,” says Spanks. “Believe me, whoever looks likely to get into power, Murdoch always makes sure he has the dirt on them in advance – it’s how he’s stayed at the top himself for so long.”

Spanks’ claims have been backed up by some top politicians. “Why else do you think we all run scared of Murdoch and News Corp? They’ve got the goods on all of us,” admits backbench Tory MP Ron Diddler. “We’re not talking misdemeanours like fiddling our expenses, or photos of us in flagrante with hookers, we’re talking about the really bad stuff: sado-masochism, drug-fuelled orgies, bestiality, even murder!” Labour backbencher Lionel Rodd agrees. “It’s the only reason everyone is so eager to get the endorsement of The Sun,” he says. “Whereas, in truth, we should be condemning that despicable, rabble rousing, sexist rag! But we don’t dare, for fear of being its next front page story!” News Corp’s grip of fear apparently extends beyond politics, reaching into all areas of public life, including the police. “Why else do you think they failed to investigate that News of The World phone-tapping scandal?” asks Spanks. “They’ve got stuff on just about every top police officer in the country – not just evidence of them beating up suspects when they were young coppers on the beat, but pictures of them selling drugs from the evidence locker out of the back of their police cars. I’ve seen with my own eyes a picture of two coppers who are both now Chief Constables, ‘spit-roasting’ a female suspect in the cells at Hounslow police station in 2002. They tried to claim that it was simply a form of interrogation used on terror suspects, like ‘water-boarding’, but how on earth was that woman meant to confess to anything with her mouth full of that rozzer’s love truncheon?”

The crux of the former News International reporter’s claims remains the porn film which supposedly features a young David Cameron. He claims that the future Prime Minister appeared in the film – known variously as Oxford Blue, Porn to Rule and The Student Ponce – when he was a cash-strapped student at Oxford University in the 1980s. “It was easy money for a good-looking posh bloke like him. I mean, you wouldn’t expect someone of his class and breeding to work part-time stacking shelves in a supermarket to supplement their meagre student grant, would you?” he says. “Besides, it paid far better than the usual student jobs. Apparently they were all at it, the only surprise is that a pretty boy like him never did any gay porn!” Spanks alleges that Cameron’s wealthy stock broker father bought up every copy of the film before it could be distributed. However, one print survived – kept by the director – and eventually found its way into the private collection of a wealthy Swiss porn enthusiast.

“Murdoch tried everything to try and get him to part with it – he offered to swap it for a free SKY TV subscription, including all the sports channels, and when that failed, he offered the Swiss guy a bevy of Page Three girls as love slaves,” Spanks claims. “But he refused to part with the film, so Murdoch decided to resort to subterfuge.” Disguised as a wealthy Arab Sheik, Spanks was allegedly sent to infiltrate the Swiss collector’s Geneva villa, on the pretext that he was selling part of Osama bin Laden’s fabled collection of rare erotic silent films – including D W Griffiths’ long-lost 1919 adaptation of the Kama Sutra, featuring Rudolph Valentino and with sub-titles by D H Lawrence – in order to generate funds for Al Qeada. “Whilst there, I was able to locate the film and swap it for a copy of Confessions of a Window Cleaner,” he says. “I doubt he’s ever noticed the substitution – he probably wouldn’t be able to tell the difference between David Cameron and Robins Askwith anyway.”

Not surprisingly, Spanks’ claims have been hotly contested, with many commentators questioning the existence of the Cameron film. “The whole story is absolutely ludicrous – it just doesn’t make sense,” declares Sunday Bystander political correspondent Conrad Bauble. “I mean, there’s no way Cameron would have been that desperate for money – he and his family are loaded, for God’s sake!” Indeed, Bauble believes that the film is simply another urban myth, sustained through internet rumours. “It’s like that story that Cameron, Boris Johnson and the rest of the Bullingdon Club were involved in the suspicious death of a prostitute at one of their wild parties – lots of unsubstantiated rumours, but never any hard evidence,” he proclaims. “Believe me, if any of these stories were true, we’d soon know about – it’s not as if there aren’t enough journalists and political fixers out there looking for this sort of dirt.”

Whilst the wizened media magnate himself was unavailable for comment, sources close to Rupert Murdoch have been dismissive of Spanks’ claims. “These are just the demented ramblings of a disgruntled ex-employee. I mean, his story is so far-fetched even we wouldn’t publish it one of our tabloids,” said one anonymous executive. “It’s obviously part of some kind of Commie poofter feminist plot to discredit News Corp. These bleeding heart liberals just can’t accept the that Rupe’s success is down to the fact that he knows what the public really wants – sex, scandal, celebrities and single issue politics – and gives it to them. People don’t want culture or complex political issues they have to think about – they want to be told what the facts are in words of less than three syllables.” The source also pointed out that News Corp had no need to resort to blackmailing powerful public figures to achieve its ends. “Look mate, we control so much of the world’s media, we could just make stuff up about them, and the kind of people who read our papers and watch our TV stations would believe it,” he says. “Or, even worse, we could just deny them any air time at all.” Spanks remains undeterred, maintaining that his revelations have nothing to do with the failure of his recent claim for unfair dismissal against The News of The World, but are instead motivated by a genuine concern the inappropriate level of influence Murdoch apparently has over the British establishment. “This is a question of who actually rules Britain,” he says. “Some bunch of over-privileged posh bankers, or some smut-peddling multi-millionaire Aussie bastard?”