UK- IT is Helen Mirren’s most controversial film – the Roman epic banned for its outrageous orgy scenes.

But now, 29 years on, the uncut DVD of Caligula is to go on sale in high street stores.

Censors decided it is not porn but a movie of “historical interest”.

The decision has shocked the movie world – and even stunned Arrow Films, the firm distributing the new DVD.

Mirren won the best actress Oscar for her role in The Queen – in which she plays the stuffy royal.

It is a world away from the decadent movie branded “insane and pornographic”.

Caligula, about the demented and perverted Roman Emperor, features hardcore, graphic sex scenes.

When the film – which also stars Malcolm McDowell, Peter O’Toole and John Gielgud – was first released in 1979, full-on sex scenes were removed.

Until now, the DVD available in this country was a sanitised version, an hour shorter than the uncut edition.

Hardcore But now the British Board of Film Classification (BBFC) have allowed the release of the Imperial Edition of Caligula, with the scenes reinstated.

Alex Agran, of distributors Arrow Films, said: “Looking at what else is getting through these days, we thought let’s try for the ultimate bete noire, the big daddy of obscene films.

“Never in our hearts did we think Caligula would get through intact but we figured a longer version would be possible. When it came back uncut, we were stunned.”

Based on Lives Of The Twelve Caesars by historian Suetonius, Caligula is the story of the degradation of Ancient Rome. But its stars had no idea how raunchy it would be.

It was scripted by acclaimed historian Gore Vidal. But producer Bob Guccione, then publisher of Penthouse magazine, thought it was too tame.

Vidal – who later insisted his name be removed from the credits – was banned from the set and director Tinto Brass from the editing suite.

Guccione hired Penthouse models and secretly filmed the sex scenes that were incorporated into the movie.

Star McDowell said: “He shot this hardcore footage two years after the film had been completed and spliced it in.

“It was absurd. There would be a shot of me smiling, looking at what was supposed to be my horse or something, then suddenly they’d cut to two lesbians making out. It was awful. We were all appalled by the final product.”

The BBFC move could open the floodgates for the release of other controversial films.

Agran said: “Censorship in the UK has taken a radical step into uncharted waters. Caligula has broken every last sexual taboo the 18 certificate once held back from public consumption.”

Sue Clark, of the BBFC, said: “We looked at the work in light of our ’18’ guidelines, which say that adults should be free to choose their own entertainment within the law.

“Given that Caligula is a film of historical interest, we felt we could pass it uncut.”