Why did the Princess of Wales go to her grave when happiness seemed finally to have found her? A woman in Cobh, Co Cork, is convinced she knows the answer to what those speculating on the matter are inclined to think may be a murky business. The woman in question is Ms Helen Barrett and she is a "white witch".

She lives under the dominating steeple of Cobh Cathedral. She is a fifth-generation witch, one of 3,500 white witches in Ireland. Only one witch, who lives in Co Kerry, outranks her. Her name remains a secret (that is her wish) but she is in her 80s and is known to those in the confraternity of witches as "An Oige".

The females of the group are witches and the males are wizards. They are the opposite to those who dwell on the side of darkness, practising other things.

What do white witches do? They can, Ms Barrett claims, summon up the forces of light to change a person's destiny. They can tell fortunes, do astral projections - better known as out-of-body experiences - and they have mastery over the elements, such as the ability to whistle up the wind. They like to think of themselves as being in the same mould as Mary Poppins.

Ms Barrett says she was born to lead and to become the all-Ireland leader of the white witches when "An Oige" passes on. She says her leadership qualities were manifested at birth, when she was found to have a particular feature on her palm. It was a set of parallel lines with crossing strokes - a ladder.

So it was written then, she says, that in her life she would take the steps that would lead to her assuming An Oige's role. She is already the leader of the Council of Elders. The number of white witches does not vary. When one of their number dies, only then is another allowed to join. Extensive study and training are required before a witch can claim to have "qualified".

But back to Diana. Some five years ago, Ms Barrett said, a friend remarked to her that the princess was very beautiful. But she was compelled to reply that Diana would die tragically in a car crash. Then, a month before her death, Ms Barrett had an out-of-body experience in which she saw the princess, the crash, the news reports, the military procession, two separate coffins, Diana and Dodi going into the Ritz Hotel in Paris.

A news broadcast on Sky television said Diana had been cut from the wreckage. She identified pillar 13 - the one into which the Mercedes car crashed. Further, she had a clear image of Diana's funeral ceremony, the arrival of her body at the Abbey, and one of her being laid to rest on the island at Althorp.

And this is Ms Barrett's challenge: these images or visions come to her only when she is in a totally relaxed state - for instance, when she is dreaming. She is now willing to undergo supervised hypnosis and to take a lie-detector test.

This test, she believes, will establish she did "see" what she claims to have seen - the session under hypnosis will establish beyond any doubt what happened that evening on a motorway in the French capital. "I am willing to swear this on my mother's soul," she said. She says that as a youngster, she foresaw the Stardust tragedy. On the very day of Diana's death, she felt an ominous pressure - a foreboding.

What else? Early into the new millennium, a tidal wave will hit Youghal, Limerick and Waterford. The Irish Stock Exchange will crash next March. The huge dam holding back the might of the River Lee in Cork will collapse.

But don't the dogs in the street know that in many parts of the world the markets are shaky and stock exchanges, to put it mildly, are jittery? "Yes, but I'm saying when it will happen here. Who else is doing that?"

You believe or you do not believe, but Ms Barrett has people flocking to her for advice on their problems and asking her to predict what may be ahead in their lives.

And so to the cynic's question. With such powers, would it not be possible to clean up on the horses? In a state of hypnosis, Ms Barrett repeated, she would have no bother in rattling off the Lotto numbers. When she was aged seven, a relative would bring her regularly to betting shops where she would scan the field and just as regularly nominate the winners. That was until her mother put a stop to it. She felt it was no place for a youngster and certainly not the way for one with her powers to go.

But what would stop her from dreaming up the Lotto numbers? Because it is something she does not choose to do, she says.

The next leader of Ireland's white witches doesn't socialise much. Doing so is too distressing. In a crowded place, she can feel the potential suffering of the people around her - those with imminent difficulties and looming health problems.

Ms Barrett is the co-designer of a ring, now being patented, that will bring joy, she predicts, to people in severed relationships who have pledged themselves to their new partners. It will be called a "Ring of Honour". Is that an advertisement? "No, for now, I can say no more."

She says her powers were handed down and she didn't ask for them. "I can do no more than offer to undergo hypnosis and take the lie-detector test."