But beginning June 19, the ultimate horror film, The Exorcist, will be re-released in cinemas in Scotland, prior to a wider UK release later this year.

Exorcist star Linda Blair describes auditioning for The Exorcist (0'19")

Other films may be as bloody and blasphemous, but The Exorcist still posseses an unearthly power to shock.

Inspired by the last official case of exorcism in the United States, the Oscar-winning film tells the story of a 12-year-old girl in a Washington household who becomes possessed by the Devil.

Possession: before

Explicit scenes show the girl, Regan MacNeil vomit a stream of green bile into a priest's face, the words "help me" appear in raised welts on her body and her head spinning 360 degrees.

The film's "creep" factor was furthered by rumours of the "curse of the Exorcist". The set burned down for no apparent reason, and several people involved with the film died suddenly, including an assistant cameraman's baby, a night watchman and an actor whose character was killed in the movie.

Possession: after

The actor Ellen Burstyn, who played the child's mother, says the film "deals with very heavy forces - I was a little worried about what that would mean."

For these reasons and others, James Ferman of the British Board of Film Classification defends his decision to ban the film.

In an upcoming BBC documentary, The Fear of God: 25 Years of The Exorcist, Mr Ferman said: "The problem with The Exorcist is not that it is a bad film - it is that it is a very good film. It is one of the most powerful films ever made.

A priest warned Jason Miller who plays Father Karras of the dangers (0'42")

"When the film first came out in the 70s there were a lot of traumatised teenage girls being helped out of the cinema, and the film stayed with them for a long time," said Mr Ferman.

But Mark Kermode, a film critic, author and presenter of The Fear of God, disagrees.

"For The Exorcist to mean anything, you have to be quite grown up. It's not a film directed at kids. It's directed at adults," he said.

"Younger people simply don't understand what all the fuss is about. They just see it as a movie with some hokey special effects."

Father Tom Bermingham, a priest who was asked to exorcise the film's set, goes even further. He believes the film can exert a positive force.

"I have no doubt that, strangely enough - paradoxically, if you will - the film was a force for good."

How many would agree is not clear. But as the old saying goes, the devil is in the details.