Alien Autopsy, a movie about the footage, is currently on release across Britain. It stars real-life television presenters Ant and Dec.

John Humphreys, a sculptor and consultant on Alien Autopsy who has also worked on special effects for Doctor Who, said it was he who made the models for the alien dissected in the original fake footage.

His confession, 11 years after the Roswell footage was first shown, will raise questions about the role of Channel 4, which unleashed Max Headroom on the world in the 1980s and bought the UK rights to screen the Roswell footage in Britain.

The footage was first exposed as a fake by The Sunday Times, but an estimated billion people still watched it around the world.

Rather than being shot in 1947 near Roswell in the New Mexico desert as previously claimed, the film was actually made at a flat in Camden, north London, in 1995.

Philip Mantle, a UFO researcher and author who has been investigating the Roswell hoax for 10 years, said Humphreys had been a prime suspect but had never before admitted involvement.

Mantle, who next month will deliver a lecture at Glasgow University on the Roswell story, said: “I didn’t think it would take so long, but I am delighted this hoax has finally been exposed and the mystery has been solved.”

Humphreys, who is based in Manchester, says he also appeared in the Roswell film as the chief surgeon. The bug-eyed alien models were filled with sheep brains, chicken entrails and knuckle joints bought from Smithfield meat market. After filming, the dummies were cut up and dumped in bins across London.

For a few short weeks the world held its breath after the 91-minute silent film was unveiled by Ray Santilli, a London-based video distributor. He claimed to have bought the footage, shot on 14 reels, from a retired American military cameramen.

Humphreys said the Roswell film was shot by himself, Santilli and three others. He said he spent four weeks fashioning the models from latex using clay sculptures.

Humphreys, a graduate of the Royal Academy who has also created special effects for the film Charlie and the Chocolate Factory starring Johnny Depp, says he only told his wife about the hoax when he was hired to work on Alien Autopsy.

“It was a very, very strange feeling to know that I had played a key part in it,” he said.

Santilli, who is played by Declan Donnelly in Alien Autopsy, insists he was trying to “re-create” a real Roswell incident. He claims he bought genuine footage that was badly damaged when it was exposed to the air after 48 years in a can. “John was given very precise images to work with and what he did was sheer genius,” he said.

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