UNITED KINGDOM. It is 30 years since the "Enfield poltergeist" hit the headlines, but it is still an event that haunts those who experienced it. As well as the Hodgson family, who were at the centre of this paranormal outbreak in their north London home, witnesses included police officers, journalists and a photographer, a physicist, and two of the Society for Psychical Research's leading investigators.

They testified at the time to the phenomena they saw and many of them repeated their statements, on camera, for a fascinating TV documentary on the case, Appointment with a Poltergeist, screened by Channel 4 in the UK (6 March) as part of its so-called "occult week".

One of the most startling aspects of the case was the production of a man's voice, seemingly that of the poltergeist, by 11-year-old Janet Hodgson. This could be explained normally, though experts were astonished that she could change her voice in this way for any length of time without doing permanent damage to her vocal chords.

Even more impressive, however, was the voice's details about himself - his name, Bill, and when and where he had died in the house where the Hodgson's were experiencing the knockings and movement of objects. The documentary included a scene in which the son of a previous tenant in the house listened to this recording and confirmed that his father, Bill, had died in exactly the manner described.

There were claims that it was all a childish prank, and two of the Hodgson children did confess to some tricks. But Society for Psychical Research (SPR) investigators Maurice Grosse and Guy Lyon Playfair testified that they were well aware that the youngsters were playing occasional tricks but there was no way they could have been responsible for producing all the phenomena, including the pulling out of a heavy fireplace from the wall.

A detailed account of the story, from a modern perspective, was featured in the Daily Mail by Danny Penman.

Maurice Grosse was the first psychical researcher on the scene and he and Guy Playfair spent well over a year helping the Hodgson family deal with the psychic turmoil they were experiencing. They had no doubt that the phenomena were genuine.

Grosse died in October 2006 [click here for obituary] , but if anything he has been more high profile, in media terms, since his passing than he was before. He gave extensive television interviews for TV programmes on London Underground's ghosts and then the Enfield poltergeist case in the last months of his life.

The screening of the Enfield programme, says his fellow investigator and author, Guy Lyon Playfair, "is just another 'coincidence' that followed Maurice's death. The transmission date was changed several times and today (6 March) just happens to be his birthday".

Guy adds: "Less than two weeks after he died I got a letter from a publisher I'd never dealt with or indeed even heard of saying they'd like to reissue This House is Haunted [their story of the Enfield poltergeist investigation], which I'd tried repeatedly for at least 10 years to get done. Maurice was far more anxious for a reissue than I was and was still banging on about it within weeks of his death. I kept saying I was trying, which I was.

"Then, out of the blue, comes a firm offer in writing. Coincidence? Knowing Maurice well, as I did for 30 years, I wouldn't bet on it."