Among those in Britain already using the drugs and hoping for a change in the way they are viewed is Anna Jones (not her real name), a 35-year-old university lecturer, who takes LSD once or twice a year. She fears that without an occasional dose she will go back to the drinking problem she left behind 14 years ago with the help of the banned drug. LSD, the drug synonymous with the 1960s counterculture, changed her life in a day, she says. ''For me it was the catalyst to give up destructive behaviour - heavy drinking and smoking. As a student I used to drink two or three bottles of wine, two or three days a week, because I didn't have many friends and didn't feel comfortable in my own skin. Then I took a hit of LSD one day and didn't feel alone any more. It helped me to see myself differently, increase my self-confidence, lose my desire to drink or smoke and just feel at one with the world.'' Many others are using the drugs to deal with chronic anxiety attacks brought on by terminal illness such as cancer. Research was carried out in the 1950s and 1960s into psychedelics. In some places they were even used as a treatment for anxiety, depression and addiction. But a backlash against LSD - owing to concerns that the powerful hallucinogen was becoming widespread as a recreational drug, and fear that excessive use could trigger mental health conditions such as schizophrenia - led to prohibition of research in the 1970s.

Under Britain's Misuse of Drugs Act it is classified as a Class A, schedule 1 substance, which means not only is LSD considered highly dangerous but it is deemed to have no medical research value. Now, though, distinguished academics and highly respected institutions are looking again at whether LSD and other psychedelics might help patients. Psychiatrist Dr John Halpern, of Harvard Medical School in the US, found that almost all of 53 people with cluster headaches who illegally took LSD or psilocybin, the active compound in magic mushrooms, obtained relief from the searing pain. He and an international team have also begun investigating whether 2-Bromo-LSD, a non-psychedelic version of LSD known as BOL, can help ease the condition. Studies into how the drug may be helping such people are also being carried out in Britain. Amanda Feilding is the director of the Oxford-based Beckley Foundation, a charitable trust that investigates consciousness, its altered states and the effects of psychedelics and meditation. She is a key figure in the revival of scientific interest in psychedelics and expresses her excitement about the initial findings of two studies with which her foundation is heavily involved. ''LSD is a potentially very valuable substance for human health and happiness,'' she said.

In a Swiss trial, the drug is given alongside psychotherapy to people who have a terminal condition to help them cope with profound anxiety. A trial in the US is examining whether psilocybin can aid psychotherapy for those with substance addiction. Professor Colin Blakemore, a former chief executive of the UK Medical Research Council, said the class-A status of psychedelics should not stop them being explored as potential therapies. A Medicines and Healthcare Products Regulatory Agency spokeswoman said: ''These products, if approved, are likely to be classified as a prescription-only medicine and also likely to remain on the dangerous-drug list, which means that their supply would be strictly controlled.'' GUARDIAN The experience

Douglas FROM the age of eight I suffered frequent and severe headaches, usually three or four a week, which caused acute pain and interfered with work and games. I first tried 200 micrograms of LSD in 1970. I had no headaches for three weeks. I then had another headache, though not as severe as usual, and the next day took another 200 micrograms. This time the headaches disappeared for six months. After that, whenever I had a bad headache I took a dose of LSD, usually 100 micrograms. My headaches have since become very rare, perhaps one or two a year. Philip FIVE years ago I had just finished my third chemotherapy session for leukaemia, which was the worst experience of my life. I didn't eat for 21 days, my weight dropped to eight stone and I was bald. I took acid at a party. I wasn't in remission, so I shouldn't have taken it, but it was an amazing experience.

It made me euphoric. I'm not religious but I had a wonderful experience, like angels coming over the walls and white clouds out of a blue sky. I thought, ''I've got to live''; it gave me the will to carry on. It gave me the strength that I could do it. GUARDIAN