Headteacher Colin Culley used to suffer from a nagging pain in his wrist. Now he says the pain has gone. And the stress of running a big primary school no longer keeps him awake at night.

He attributes his new-found sense of wellbeing to a small but powerful magnet which he keeps strapped to his right wrist. It looks just like a watch, but it’s worn the other way around so the magnet lies against the pulse.

He is one of a growing number of people practising magnotherapy - a controversial alternative therapy which claims to use magnetic fields to aid healing.

Those who espouse it - and they include GPs - believe it can alleviate pain and stress in a range of ailments. But others in the medical profession dismiss magnotherapy and put its apparent successes down to the placebo effect.

Mr Culley, head of Malton County primary school in North Yorkshire, is an enthusiastic convert. His wife Sandra - a former teacher - also swears by magnets. She had mild arthritis in her hands for many years, but since she’s worn the magnetic wristband, she no longer suffers from it.

Even the couple’s once-lame dog wears a collar containing magnets. “It started with our 13-year-old Labrador, who has bad arthritis. We were a bit doubtful, as everybody is - we didn’t know anything about magnotherapy. But we bought a special collar for her - and she was transformed within a day. She was able to go for walks and became much more playful.

“I used to have a pain in the bone in my wrist. That’s gone. And I certainly sleep soundly. I’m sure that’s because I’ve been wearing the bracelet.”

Mr Culley particularly recommends the magnetic bracelets to help overcome the stress of teaching. One of his staff is now wearing one to help overcome back pain. “Being head of a primary school with 325 pupils can be stressful,” he says. “The worst side of stress for me used to be going to bed thinking about problems at school. Now I sleep soundly.”

On an industrial estate in Saltash, Cornwall, is the headquarters of Ecoflow, the UK’s largest manufacturer of magno-therapy products. And business is booming. The company makes a range of magnetic bracelets and similar products for people and animals. It has an annual turnover of around pound;14 million in retail sales and each week turns out an estimated 24,000 items, which sail through a network of distributors.

Ecoflow was founded by husband and wife Nigel and Paula Broderick, whose journey into alternative health products followed an unusual route. They started manufacturing a magnetic device to reduce fuel consumption in cars, and their sales staff carried magnets with them to give demonstrations.

“They were coming back telling us their aches and pains were disappearing,” says Mr Broderick. This prompted them to start investigating the use of magnets for health purposes. There found “there was no explanation as to how or why it worked, apart from sensationalist stuff, mostly from the US”.

In fact, there is no established scientific theory to support magnotherapy, but the Brodericks were not put off. They have put forward their own claim that magnotherapy works because magnetic fields can interact with a body’s cells and trigger changes in the way they operate.

In its blurb the company maintains that Ecoflow is “a life-changing experience”. And it claims magnotherapy has help-ed relieve a range of conditions, including arthritis, poor circulation, migraines, and spondylitis (inflammation of the spinal vertebrae). Mr Broderick says the therapy is completely safe, and the company receives letters by the sackload from users reporting improved health.

“When we started, an obvious criticism was that it was psychosomatic. We thought if that was the case, people were in pain and now they’re not. And even if they just think they’re not, it gives them a better quality of life.”

Sue McVeigh is a 56-year-old former headteacher who retired 15 years ago. Her story seems almost incredible. Until three years ago she suffered badly from arthritis in her hips, knees, neck and shoulders. “I was thinking we would have to sell our house and buy a bungalow,” she says.

After initial scepticism she tried a magnetic bracelet. “With-in five days I could go up and down stairs. Within 10 days I could run upstairs. I have avoided all medication yet now I have no arthritis - at all.”

Despite such stories, magnotherapy is arousing deep suspicion in some areas of the medical profession. Healthwatch is an independent charity that monitors all forms of treatment and aims to inform the public.

Its chairman, Professor John Garrow, former professor of human nutrition at Bart’s Hospital in London, says the responsibility is on companies producing magnotherapy products to conduct proper clinical trials before selling them.

He maintains: “The chances that wearing a wristband with a magnet in it will do you any harm are negligible. The chance that it’s a waste of money is very high. There’s no obvious reason why wearing a magnet positioned over your pulse or your wrist should make the slightest difference to arthritis.”

How does he account for the apparent success stories? “The placebo effect and reporting bias. If you have a magnet in a wristband and a friend persuades you that maybe it will help your arthritis, and you part with 50 quid, you have an emotional investment. It would be a shame wouldn’t it if it made no difference.

“Some people will get better, some people will get worse and some will stay the same. The people who stay the same or get worse will not go around saying ‘Gosh, I was fool enough to spend 50 quid and it had no effect’. But those who spent 50 quid and got better will go around saying ‘this is fantastic’.”

Colin Culley believes the last word goes to his pet Labrador. “You cannot explain it,” he concedes. “But the turning point for me was the way if affected the dog. She doesn’t know what she’s wearing. If I take the collar off her, within a couple of days she starts limping. When I put it back on she’s fine.

“I accept that people might not believe it. But if you have a pain why not try it? You have nothing to lose?” Ecoflow, 21 Brunel Road, Saltash Industrial Estate, Saltash PL12 6LF. Tel: 01752 841144

* So how does it work?

Reliable information about the history of magnotherapy seems hard to come by. A trawl on the internet brings up many wild and usually unverifiable claims. And in its own publicity material, Ecoflow for example, claims that Cleopatra used magnotherapy to help preserve her beauty.

Dr Vladislav Vaclavek is a scientist, vet and author of ‘Magnotherapy - the pHacts’. He says that many theories have evolved as to how magnotherapy works in the absence of any scientifically acceptable explanation. His own belief is that the benefits of magnotherapy come from a change in the body’s pH - the balance between acid and alkali - triggered by magnetic energy.

Dr Mark Fernell, a GP in Rubery, Birmingham, wears a magnotherapy wristband himself and encourages patients to use it for certain conditions in which orthodox medicine has failed. Now he is trying to set up proper clinical trials.

“Ridiculing it is easy,” he says. “I have been qualified for 20 years and I keep an open mind. I have seen things with this particular mode of therapy that I believe merit further investigation.”