SITTING in her study Jane Welbourn works away under the watchful eye of her father. He's sitting in a chair nearby. Nothing unusual in that, countless fathers are there for their children, particularly in times of need. The difference this time is that Jane's father died last April.

"We have a room where I work and he sits there," says Jane, of Aldfield, near Ripon. "I was ill yesterday and he came with a message for me. It's amazing really.

"I was absolutely devastated when I lost my father and I went to see someone about it. I was told my father couldn't rest properly because I was absolutely demented with grief. Now I can see his shape and get a lot of peace from it."

She's not the only one. As a clairvoyant, she helps countless people come to terms with the deaths of their loved ones by passing messages on from the spirit world.

One woman went to see her after the death of her husband who had hanged himself. "He followed her through the door," she recalls. The message she was able to pass on gave the woman great peace of mind. Conversely, when the family has come to terms and the spirit is at rest, she is unable to contact them.

Recent research which has provides the first scientific proof of the afterlife comes as no surprise to Jane, who discovered her special ability when she was 13 and lost her brother in tragic circumstances.

"There is definitely an afterlife - I'm a firm believer," she says. "In fact I get quite a few scientists coming to see me with things they want verifying."

All over the world, thousands of people claim to have journeyed into a world beyond death and returned to tell the extraordinary tale.

Parapsychologists call these accounts near death experiences, or NDEs. Typically they occur when someone has suffered a heart attack or is lying on the operating table with surgeons fighting to save them.

When the person is resuscitated he or she recalls, in startling detail, having a glimpse of the afterlife before being pulled back to Earth.

Every story is different, but there are strange similarities common to almost all.

These generally involve travelling through a tunnel towards a source of bright light, meeting dead loved ones or angelic beings and undergoing some kind of life review.

Hard-headed scientists have dismissed such experiences as hallucinations caused when the brain starts to shut down during the process of dying.

A group of doctors at the University of Southampton have reported findings which they claim to be the first scientific evidence of life after death.

The team spent a year studying people resuscitated in the city's hospital after suffering a heart attack. The patients brought back to life were all, for varying lengths of time, clinically dead, with no pulse, no respiration and fixed, dilated pupils.

EEG studies have confirmed brain function ceases when such symptoms are present. Yet seven out of the 63 patients who survived recalled emotions and visions while they were "dead".

The patients were interviewed within a week of their cardiac arrest and asked if they remembered anything during their period of unconsciousness. Seven reported some NDE features, and four reached the strict criteria used to classify genuine NDEs.

They recalled feelings of peace and joy, time speeding up, heightened senses, lost awareness of body, seeing a bright light, entering another world, encountering a mystical being or deceased relative, and reaching a point of no return.

The researchers were unable to offer a rational and scientific explanation for their results. None of the patients had been starved of oxygen, which some experts believe may be responsible for NDEs.

Dr Sam Parnia, who led the study, believes the mind might be independent of the brain. He says: "The brain is definitely needed to manifest the mind, a bit like the way a television set can take what essentially are waves in the air and translate them into picture and sound."

Researchers were so intrigued by what they discovered that they have now set up a new charity, the Horizon Research Foundation, to fund more studies into near-death experiences.

These are said to be becoming more common, largely due to advances in medical science which make it more likely for people to be rescued from the brink of death. A 1982 Gallup poll estimated at least eight million adults in the United States alone recalled having an NDE. The figure is now thought to be closer to 13 million.

But such experiences have been reported for centuries, from all cultures and religious traditions. One of the remarkable things about near-death experiences is that they share underlying patterns that are unaffected by the person's culture, religion, race or education.

Moving through a dark space or tunnel is one of the most common experiences, as is encountering a golden or white light imbued with love or Godliness.

A life review - seeing and re-experiencing major and trivial events combined with some kind of judgement of how that life was lived - is another frequent experience. So is having a sense of immense understanding - being made aware of how the universe works.

Usually NDEs are intensely and pleasantly emotional. People report blissful feelings and being overcome by indescribable love and joy.

But not all of them are like this. A number of people have reported horrific and terrifying experiences, including being thrown into a vast and empty void and being tormented by demons and monsters.

So is this evidence for the existence of heaven and hell? If so, the criteria for entering either realm seem a little hard to understand.

Those who have encountered frightening NDEs invariably cannot understand what they did to deserve them.

The Tibetan Book of the Dead is an ancient manuscript which describes what a person can expect to encounter when they die.

It was written by Lama priests who claimed, through advanced yogic training, to remember not only their last incarnation, but their passage through several stages of an afterlife before being reborn.

There are many similarities between the descriptions in the Book of the Dead and near-death experiences. At the point of death, the book says, a person sees a clear light, identified as the ultimate embodiment of Godhead.

Encounters with Peaceful Deities also echo the meetings with mystical beings in NDEs.

But disturbingly the Book of the Dead also talks of meeting Wrathful Deities, and terrifying experiences which sound like a vision of hell.

Here, hell is not a punishment but simply another stage in the after-death journey, and one only encountered after a person has been dead for a while.

The Tibetan monks describe all these phenomena as illusions, which is a reminder of the hallucinatory explanation for NDEs. The Tibetan tradition says the afterlife is no less real than the material universe, which is also believed to be an illusion.

Sceptics such as psychologist Dr Susan Blackmore, at the University of the West of England in Bristol, are certain NDEs can be explained by neurochemistry.

Neural noise, caused by random sparking of neurones in a dying brain, could explain the common experience of travelling down a tunnel towards a bright light, she believes.

Dr Blackmore attributes the feelings of extreme peacefulness often reported in NDEs to the release of endorphins - natural opiates - in response to extreme stress.

Colleague Dr Karl Jansen, from St Thomas's Hospital, London, claims to have reproduced NDEs with ketamine, a hallucinogenic anaesthetic.

He maintains the drug can reproduce all the main NDE features, including travel through a dark tunnel into a light, out-of-body experiences and communing with God.

No one can say at present whether NDEs are biochemical hallucinations or something more mysterious. But ultimately, the riddle will be solved for all of us - when we die.