Deborah Sundahl has made a career out of, literally, bringing female ejaculation into the open, says Julia Stuart

On Sunday, a 50-year-old woman is going to stroll into Soho House in London and do something decidedly un-British. Deborah Sundahl will first tell paying members of the public how to find the G-spot. She will then give precise instructions on what to do once it is located, including how to achieve female ejaculation. Any doubts in the audience as to whether such a thing is possible will be dispelled when Sundahl promptly lifts up her skirts and gives a demonstration.

For many, the notion of women being able to ejaculate is as foreign as the location of the G-spot. A veil of ignorance is still kept tightly draw over women's sexuality, despite the famous scientific studies, the Meg Ryan moment and the word "vagina" running amok in theatreland.

The G-spot, a sensitive area that can be felt through the front vaginal wall which is said to increase female pleasure, was not identified until 1944, when German gynaecologist Ernst Grafenberg first described the area and its potential in a scientific journal. The discovery was largely ignored until it was named after him by American sex researchers Dr John Perry and Dr Beverly Whipple. Their book, The G-Spot and Other Recent Discoveries About Human Sexuality, co-authored with Dr Alice Ladas and published in 1982, became an international bestseller. It is being republished in Britain in January.

But, clearly, many remain baffled. Coco de Mer, London's poshest sex shop, hopes that by inviting Sundahl to host one of their talks, discreetly named "salons", at least some brows will be unfurrowed.

Sundahl's pedigree is more hands-on than scientific. In 1985 she founded On Our Backs, an erotic magazine aimed at women, which was published for 10 years. She has also worked as an erotic dancer and held classes teaching women how to strip for their lovers. For the past 15 years she has been holding workshops in America during which she and her students locate their G-spots. Her new book, Female Ejaculation and the G-Spot, works on the premise that the G-spot is in fact the female prostate. It is a claim already made by scientists. At its 2001 meeting in Orlando, Florida, the Federative International Committee on Anatomical Terminology agreed to support the use of the term "female prostate" in its journal Histology Terminology.

Dr Milan Zaviacic, professor of pathology and forensic medicine at the Comenius University of Bratislava, Slovakia, conducted extensive studies on the female prostate from 1982 to 1999. He determined that it had two functions: to produce prostatic fluid and hormones. Whipple, professor emeritus of Rutgers University and vice president of the World Association for Sexology, who has analysed the fluid, which is expelled into the urethral canal, says it looks like watered-down fat-free milk, and tastes sweet as it contains fructose and glucose. Published studies by her and Perry, which she says have been replicated by others, show that its chemical composition is different from urine from the same subjects.

The theory that women are capable of ejaculating is nothing new. The Greeks and Romans believed that both male and female fluids contributed to the creation of life and it is featured in the Karma Sutra. Sundahl's book offers techniques in "how to get this lovely feminine fountain flowing again". It is achieved, she says, by stimulating the G-spot and then just pushing. "Every woman who allows that to happen and brings it into their sexual life, and every man who has experienced it, absolutely loves it," she claims.

Women can emit ejaculate fluid when simply aroused, she says. "You don't have to orgasm to ejaculate. You can control ejaculation. What happens is that men don't control it at all and women control it almost completely. Because we have no information, we think that it's urine and the last thing a woman wants to do when she's having sex is to feel like she's peeing. Many, many, many women have had this experience at least once in their lives and they've shut it down.

"And that is at the heart of what I'm doing in my workshops - to get this working again. Many women do not even allow themselves to feel pleasure or have an orgasm because they are afraid they are going to ejaculate, ie pee. Not to mention that they think they have urinary stress incontinence so they go and get surgery, or they're clamping down on the ejaculate and having bladder infections."

Sundahl believes most women ejaculate, but not all are aware of it. A study conducted in Spain in 1997 by sexologist Dr Francisco Cabello Santamaria suggested that many women's ejaculate simply stayed in the urethra as the amount was so small, or it retrograded into the bladder.

Whipple says it is not known what the purpose of female ejaculation is, other than it can be pleasurable. "In some women it heightens orgasm, in some it doesn't. We are all unique individuals. It doesn't make any difference [whether you ejaculate or not]." She believes one of the reasons women's sexuality is still shrouded in mystery is because it is easier for scientists to research men's. "They have an organ that sticks out and it's easy to measure, and most researchers were men so they were interested in male sexuality."

Whipple has some misgivings about Sundahl's book, in particular her claim that women can ejaculate up to a cup and a half of fluid. "I don't know what it is that she calls female ejaculate, it may be urine because the amount is so large. We have only measured 3-5ccs in all of our research studies that we have analysed. I don't see how that much can be produced by the female prostate gland. She has no analysis of the fluid."

Nevertheless, Whipple welcomes the fact that female sexuality is being discussed. In an age when CNN can run a 20-minute profile of Eve Ensler, the author of The Vagina Monologues, without once using the word vagina, many women would agree.

'Female Ejaculation & The G-Spot' by Deborah Sundahl is published by Fusion Press, £10.99. To reserve a place at the Coco de Mer salon call 020-7267 9700. Tickets cost £149

Myth or magic? The truth about the G-spot

Alan Riley, professor of sexual medicine at the University of Central Lancashire

"It's true that some women have an area in the front wall of their vagina which is meant to be erotic for them, which has been called the G-spot, and that some women do eject fluid if this area is stimulated. It's important to recognise that not every woman has this response. We mustn't build up people's unrealistic expectations and make them feel they are abnormal if they don't.

"I won't go as far as saying that women have a prostate. Certainly, very small cells have been identified in the G-spot, some of which may produce chemicals that are found in the male prostate. But in no way can we describe this area as the prostate.

"It's incredible that we are at the early stages of understanding female sexual functioning. We need to understand much more about it."

Dr David Devlin, a specialist in sexual health and co-author of The Big O

"There is no doubt whatever that in quite a lot of women there is an area in the front wall of the vagina which, when stimulated, produces very pleasant sensations and may help the woman to reach orgasm.

"I very often have queries from women who are very embarrassed because they produce fluid at orgasm. It's very important to reassure them that for a lot of women this is normal, it may well be a fluid produced by these glands around the urethra. It could also be urine. But the great point is that it doesn't matter very much if you accept it for what it is. It's a normal phenomenon at climax.

"What a lot of women also don't tend to realise is that a lot of male partners actually like this. They think that it shows that the woman is very highly sexed or that the man has done a very good job."