Jokes, discomfort and back pain - very large breasts are not the asset that many might imagine. For some, their size leads to psychological afflictions. Yet reduction surgery remains rationed by the NHS. Glenda Cooper hears the story of a woman who had the operation done privately.

In the end it was the bridesmaid's dress that did it for Rachel McDonald. She decided to have the operation in despair after she was chosen to take part in her sister's wedding. "I was going into all these shops trying on bridesmaid's dresses and there was nothing at all that fitted properly," she said. "It was just a joke."

Mention the phrase "breast reduction" and you are likely to get two responses: sniggers from men and jealous remarks from less well-endowed women. But for women whose cups runneth over like Rachel's, it is far from a laughing matter. Breast reduction now accounts for one in five breast re-shaping operations in the UK.

Celebrities such as Katie Boyle have gone under the knife - her operation was a Christmas present from her partner, Peter. "Before, I wore bras the size of hammocks. I was a 44DD, suffered back pain and had to think twice before turning over in bed," she has said. "Now I'm a much more comfortable 36D. I have no regrets. To me, it's bliss."

Diane, originally a size 36DD, said: "I used to make a joke about it. At school I escaped a lot of teasing because I used to cover up, wear sloppy jumpers and cardigans. I could never wear anything tight-fitting. I suppose I'd laugh about it with close friends but I didn't like it. I felt uncomfortable with myself.

"You got fed up when you talked to men. You would make eye contact but then their eyes would always travel down to your bust. So I never wore anything revealing an inch."

The main reason why women go for what can be the kindest cut is undoubtedly because they feel self-conscious and embarrassed. But they experience more than just mild discomfort. Some become so unhappy that they develop eating disorders trying to do something about their bust.

A survey of 100 breast-reduction patients by Harley Medical Group found that six out of 10 had suffered extreme anxiety in their teens as a result of teasing at school. Half said they had felt so self-conscious because of their breasts they could not go out with friends or meet new people. One in 12 complained of sexual harassment in the workplace and 4 per cent said they had suffered from eating disorders.

Many women experience physical discomfort as well. Most of those taking part in the study said they had had chronic back pain and nearly half had suffered ridging in the shoulders caused by the pressure of their bra straps. Add to that the facts that some suffered pain from elbowing their breasts in their sleep and many were unable to participate in sports and the extent to which women can become because of their breast size become apparent.

The survey echoes findings reported in the British Medical Journal which called for more breast reduction to be available on the NHS. Cosmetic surgery is one of the few areas of healthcare being explicitly rationed, but researchers from Oxford said that breast reduction was more than an aesthetic treatment. In a study of 166 women who had the size of their breasts surgically reduced, they found that 86 per cent reported substantial improvements in physical, social and psychological wellbeing.

After the operation, almost nine out of 10 said they saw a great deal of change in their appearance and described the surgical result as either excellent or very good. The proportion judged at risk of depression or other mental disorder fell from 41 per cent to 11 per cent.

The research team, led by Ray Fitzpatrick of the Department of Public Health at Oxford University, said that the findings should make those health authorities who deny women the operation think again.

Diane first of all went to see her doctor to see if she could get the operation done on the NHS. "She said I could go on a waiting list but I'd be looking at a two-and-a-half to three-year wait," she said. "Once I'd made up my mind I just wanted it done then and there. I'm 29 now, I had a good job and I could afford it so I thought to go private was the answer. I wasn't worried at all about the thought of having a major operation although I didn't know what it entailed."

It cost her pounds 5,000. "It was money well spent. I don't regret spending it at all." She went for her first interview in November 1996 and this time last year underwent the operation. "The surgeon warned me that I shouldn't expect miracles and it would take months before my breasts got back to a normal shape, because of being held down by tight bandages. In the end it took about five to six months."

Peter Ashby, the surgeon who carried out the operation on Diane at Harley Medical Group, said: "For well-endowed women who have a slim build they can be a great nuisance - they are heavy, uncomfortable and in the summer they can get very hot underneath the bust. Simply running for a bus can become embarrassing. Ladies with double D, E and F cups look at ladies with A and B cups with great envy. When I do breast enlargements and small- breasted women ask for D cups I always tell them that they would find them very uncomfortable and the ideal would be a B or C."

Breast reduction, he adds, is however a major operation; it takes around two to two-and-a-half hours and "it is not an operation that should be attempted unless you know what you are doing. It has many pitfalls". The surgeon must be careful to cut the breast so that the shape is retained, with the nipples in the right place "and not miles away".

In Diane's case, when reducing her to a 36C he removed 1.4kg from her breasts. That is by no means the most he has removed - one woman had 1.6kg removed from each breast. "She was very pleased," he says.

Diane added: "I was so pleased to have the operation done. I didn't tell everybody I was having it done but my close friends and family said I looked great and they didn't blame me for getting it done. People who didn't know me well just thought I'd lost weight.

"I went out and bought a whole new wardrobe with all these tight-fitted tops I'd longed to wear. Bikinis had always been my worst problem. Now I've gone out and bought two! The operation has made such a difference to my life and my confidence."