ANYBODY who walked into a roomful of transsexuals would immediately be struck by the spectacle of tiny men and enormous women. It is one of the many strange facts about the phenomenon that male-to-female transsexuals are, in their original gender, taller than the average man, while female-to-male transsexuals - women who believe they are 'really' men - tend to be shorter than the average female.

But wait a minute - a roomful of transsexuals? How likely is this? Surely such exotic creatures are rarely sighted?

At one time, perhaps, but not any more, at least not so far as male-to-female transsexuals are concerned. Consultant psychiatrist Dr Russell Reid, of Hillingdon Hospital, Middlesex, says he now sees at least three transsexuals a week, and the numbers are growing. In particular, he treats an increasing number of elderly men who want to live out their retirement as women.

'These people have bottled up their desire for so long, and now want to be truly 'themselves'. Many of them make extremely successful and convincing women,' he says.

Over the 12 years that Dr Reid has been specialising in the treatment of trans- sexuality, he has come to see that there are many strands to a syndrome in which a biologically normal man or woman persists in the belief that he or she is 'really' the opposite.

For one thing, Dr Reid says, there are two basic types of male-to-female transsexual - the primary and the secondary.

'Primary transsexuals, including such high-profile campaigners as Caroline Cossey and April Ashley, are almost always extremely beautiful and fine-

featured. As boys, they were effeminate and attracted to other males. These are males who make the changeover very early, usually before adulthood.

'Post-operatively, they usually want to marry and settle down as normal women, as far as possible.'

But these are a minority. By far the greatest number of male-to- female transsexuals, says Dr Reid, are of the secondary type - heterosexual men who have married and fathered children and who often hold down important, traditionally masculine jobs, such as engineering and flying. Typically, they will make the change in their forties or fifties.

Before this, they seem perfectly normal, masculine men. They are not effeminate, not gay, and are often extrovert, witty and high- achieving. But all their lives they have been hiding a terrible secret - an overwhelming desire to cross-dress from time to time.

'Every now and again,' says Dr Reid, 'these secondary transsexuals will just have to dress up in women's clothes and go out, even though they know this can be dangerous. My own view is that their gender dysphoria often emerges as a kind of mid-life crisis.'

But once they have made the change to live full-time as women, they hardly ever bother to look glamorous. Many never wear make-up, and live in trousers and sweaters. But they are now women, not men, and this gives them a new lease of life, a new calmness and serenity.

'The massive doses of female hormone they take - around six times that of HRT (hormone replacement therapy) for biological women - has the effect of tranquillising and sedating their emotions,' Dr Reid says. 'But, on the whole, they remain go-getters, people with a passion.'

There is also the inescapable fact that taking female hormones gives them a new lease of life. 'Oestrogen has the effect of softening the skin and reducing body hair,' Dr Reid explains. 'It also makes them look years younger. I see many transsexuals in their seventies who you would take for women of 50.

'They are also better treated as women than they would be as men. Older men are usually considered a nuisance, whereas old ladies are looked after. When did you last notice anybody helping an old man across a road, unless he was blind?'

Although all primary transsexuals form sexual relationships with men - or want to - there is a wide variety of sexual orientation among the secondary types. An increasing number now remain married to their wives, and live as two women together. Some embark on relationships with men, while others are attracted to women and live as lesbians. It is not unknown for two post-operative male-to-female transsexuals to set up home together.

Male-to-female transsexuals may have their male organs surgically removed and an artifical vagina constructed. This operation has been performed now for more than 40 years and is very successful. Female hormone enables them to grow breasts, but most have silicone implants as well.

With female-to-male transsexuals, a different picture emerges. 'People tend to imagine that female-to-males are mirror images of males-to-females,' Dr Reid says. 'But nothing could be further from the truth. For one thing, all female-to-males tend to follow a pattern. They are girls who have always been tomboyish, and refuse to wear skirts or dresses. I've known some who won't even go to a relative's wedding if they have to wear a skirt.

'They rarely have boyfriends or become interested in girls' matters. They can't identify with other girls at all, yet they are not usually conspicuously masculine in their behaviour.

'For instance, you will never see a female transsexual drinking and smoking and throwing her weight around. Nor do they take particularly masculine jobs, but tend to be social workers, teachers, perpetual students. I have never yet met one with a high-flying career as a woman, whereas the male-to-female transsexuals are often enormously successful in their jobs as men.

'And whereas the male-to-female transsexual gets sexual pleasure and tremendous relief from cross-dressing, there is no sexual element at all for the female-to-male. She won't wear women's clothes under any circumstances, whereas the male-to-females are happy to wear suits and jackets and ties before the change-over.'

There are also sexuality differences. 'Although many male-to-females have girlfriends, most female-to-males never have any sexual relationships with men either pre- or postoperatively,' says Dr Reid. In order to effect the change, they have to take huge amounts of the male hormone, testosterone. 'This works to deepen the voice, develop facial hair and muscles on the body. There are also mental effects in that they have more energy and need less sleep.

'The effect of male hormone is to make female-to-male transsexuals more pushy and aggressive, although it doesn't make them more effective in the outside world. They often get angry more quickly.' Surgically, female-to-

males have their breasts removed - these are always the feature they hate the most - and a hysterectomy. Most do not have a constructed penis, as the operation to perform phalloplasty is still experimental and, usually, not cosmetically acceptable.

Why is transsexuality, both ways round, becoming more common? Dr Reid believes it's because society is losing its horror of it. 'It is becoming more accepted, and doctors and psychiatrists are more sympathetic. Also, far more is known about the condition nowadays. Although we still haven't discovered what causes it, we do know that the wish to change is overwhelming, something that can never be 'cured'. Nobody ever embarks on this journey lightly - only when they feel they simply have no choice but to live permanently in the new gender role.

'I would say that around 95 per cent of post-operative transsexuals are completely happy and satisfied after the changeover. Only about 5 per cent ever regret it - even when they lose their family, jobs and homes, as is frequently the case.'

Further information is available from the Beaumont Trust, BM Charity, London WC1N 3XX.