When Glenda Cooper went to a hypnotherapist to end her affair with Nick O'Teen, she found will-power playing a surprisingly important role; He was enthusiastic, and assured me that I'd never want to smoke again. Wildly keen on the idea of an addiction-free life, l got off the phone and immediately lit up
Giving up smoking is as difficult as giving up heroin, they say. But at least when you are coming off heroin, no one expects you to hold down a job, have a mature relationship or decide what to wear in the morning. This is why, one recent morning, I found myself in a small, bare, claustrophobic room, listening to a light voice ask continual questions while I sat in a chair with my eyes closed. I was being hypnotised to help me give up the weed.

There was no gold watch swung in front of my eyes, no mantra of "you are getting sleepier ... you are asleep" and no Freud-style couch. I remained awake throughout the whole process - or rather, in that curious state just before drifting off to sleep at night, or first thing in the morning, when you are acutely aware of your surroundings but cannot communicate with others.

With thousands of smokers trying to quit each year, hypnotherapy is a boom industry; there are an estimated 4,000-5,000 practitioners in the UK. Its popularity with smokers stems from its promise of the ultimate "quick fix", with many therapists offering a one-off session to alter the subconscious. The life-long love affair with the weed, it is claimed, can be broken off painlessly overnight.

A 20-a-day woman myself, I had tried everything to give up smoking permanently. The latest effort was at New Year where I tried nicotine patches and then gum. (Warning - when the packet says "do not smoke when wearing a patch", take it seriously unless you enjoy feeling sick and dizzy. I gave in when I realised that I was absent-mindedly putting gum in my mouth seconds before lighting up.)

Hypnotherapy was not something I was keen on initially. My subconscious is, I am sure, quite weird enough without anyone tampering further with it. I have always been deeply suspicious of statements such as: "the subconscious is retrained to transfer the satisfaction of smoking to a more advantageous role which will increase vitality, improve health and benefit the mind, body and spirit".

This is what Christian Pereira said on his press release which challenged journalists to "Stop Smoking in an Hour". Taking up his offer of a free treatment, I went to see him at a plush health club for ladies who lunch in Covent Garden where the charge for his treatment is pounds 250.

We had spoken briefly on the phone first while he established how long I had been a smoker, how many cigarettes I puffed each day, and the principal reason for giving up smoking - not, in this case, the well-established link between cigarettes and lung cancer, but a recent survey which revealed that smokers age faster than their non-smoking brothers or sisters.

He was enthusiastic, and assured me that I would never want to smoke again following the treatment, although he did add it might be necessary to have a back-up session. Wildly keen at the thought of an addiction- free life, I got off the phone and immediately lit up to celebrate.

Four days later, I sat in this small, ascetic room - miles away from the luxury I had somehow expected - very nervously listening to how the therapy would work.

The process is simple. You do not fall asleep - you remain awake and alert at all times; and, no, I did not end up thinking I was a chicken or doing anything bizarre. Quite simply, with my eyes closed, I had to tense and relax every muscle in turn before imagining myself in a beautiful, serene garden in which there were five steps. Every time I stepped down one, I would feel more relaxed.

Then the therapist planted the "suggestion" in my subconscious, pointing out the bad points of smoking and the good points of non-smoking. I was told to visualise my life as a smoker and a non-smoker. What would cigarettes do to me physically if I didn't give up? Would they make me look older? Turn my teeth yellow? How will my family and friends feel?

Conversely, how free will I feel once I give up? What will be the benefits? How much healthier will I feel? Listening to my answers later on tape, I note that I sound slowed down - as though the cassette batteries were beginning to run down.

The therapy then moved on to visualisation techniques. I had to imagine a room I knew with a table in it, and then piling all the packets of cigarettes I had ever smoked on top of it. I don't know how much of a trance I was in because I found it extremely hard to quantify - scarily so. I then had to imagine setting fire to all said cigarettes and the acrid smoke filling the room.

After going out through the door, I then had to re-enter, get rid of all the cigarettes, open the window, look around at the bright, clean room now devoid of anything to do with smoking, and enjoy the clear air.

The final stage of the treatment was to picture myself on a television screen, first as a smoker, over the next six months, 12 months, two years, five years, to imagine how I would look, how I would feel, what friends and family would think of me and what it would cost me.

Conversely, I then pictured myself as a non-smoker (by this time, my mind was disobeying me slightly and I had to force myself to take away the cigarette in my imagined hand). After I had answered all these questions, Mr Pereira told me, after counting to five, to open my eyes. I did so, and that was that.

Coming out of hypnotherapy, I left the club feeling, well, slightly depressed. There were no feelings of euphoria, and no conviction that I was going to quit. By the end of the day, my craving for a cigarette had become unbearable, as had the misery I felt. I spent the whole evening in floods of tears, depressed about everything and the insurmountable problem of ever quitting.

I stomped through the next day, miserably ticking off the times I would normally be having a fag. Everything seemed too much effort. I could almost taste a cigarette. Invited out for a meal, I declined, feeling that it would be unbearably cruel to inflict myself on anybody, and went home to alternate between sullen depression and weepiness.

This pretty much set the pattern for the next seven days. There was a gnawing conviction that the evil Nick O'Teen would never let me go, as well as a string of impossibly stressful events, including the inevitable ex-boyfriend, overwork and sanctimonious comments from non-smokers, to cope with.

It certainly didn't feel like the magical solution I had hoped for. Experts I talked to said therapists commonly offer one treatment for smoking because that is what the public expect, although frequently they give extended treatment or back-up sessions if you feel you need extra help, according to William Broom, secretary of the National Council for Hypnotherapy.

"The public tend to have high expectations after watching stage hypnotists such as Paul McKenna," he said. My experience, he added, was not atypical; not everyone finds hypnotherapy a positive experience.

The percentage rate of success is probably less than half, according to Dr Michael Heap, lecturer in clinical hypnosis at Sheffield University. He adds, though, that it is still probably the most successful of all treatments for smoking.

The best results, he says, occur when someone has made the decision themselves without being pressurised by someone else, and when they have paid for it themselves (the average fee for a session is between pounds 50 and pounds 100, he suggests). Having a live-in, non-smoking partner helps, as does back-up support from the hypnotherapist. Dr Heap called for a national registration of therapists and nationally accredited training courses; picking a therapist is more a matter of judgement than luck.

When I told Mr Pereira of my experience, he immediately offered a free back-up session, and said that he had never come across anyone reacting in the way I had. He said he had 95 per cent success rates and on the matter of costs was always happy to consider discounted rates.

As you read this, I will have gone nearly a month without smoking. But it hasn't been easy - I've suffered hellish withdrawal symptoms and felt miserable into the bargain. Although hypnotherapy may have played a part, it didn't work quite as easily as I expected and will-power has certainly helped to pull me through. What now stops me smoking is the weeks of hell I went through after giving up. I couldn't bear to do it again.