I'll have what she's having

YES. YES. YES. Women apparently at the point of orgasm are featured in a new TV ad campaign. And Yes. Yes. YES. It's OK for it to be shown before everyone has gone to bed.

Ever since Molly Bloom scandalised the nation by enjoying pages of ecstasy in James Joyce's Ulysses, depictions of female sexual pleasure have been getting moralists hot under the collar.

From Jane Birkin reaching a breathy climax in 'Je t'aime, moi non plus' to Donna Summer moaning suggestively in 'Love To Love You Baby', the thought of women engaging in sexual abandon has always seemed to trouble the censors.

In recent decades, of course, attitudes have become more liberal. Yet while Meg Ryan's famous faked climax in When Harry Met Sally way back in 1989 is one of the most popular film scenes of all time and the four friends in Sex In The City had orgasms almost as often as they bought new shoes, graphic portrayals of female sexual pleasure have never really carved themselves a niche in mainstream UK television.

But now Durex has come up with an advert for its female "pleasure gel", which consists of a montage of women apparently in the final throes to the soundtrack of the 'Queen Of The Night' Aria from Mozart's The Magic Flute. More provocatively still, some of the women seem to be getting their kicks without the aid of a male partner (the tag line, after all, says Durex Play O is "all you need").

The new advert is far raunchier than previous Durex efforts, which concentrated on the functional rather than the fun and used humour to avoid the embarrassment factor.

But last week the ASA ruled that – although the new advert had been given clearance by Clearcast (the body that passes TV adverts) to be broadcast after 11pm – Channel 4's decision to show it earlier was not misguided as it was "not overly graphic, contained no explicit material and was unlikely to cause offence". To some, the move marks a sea change in attitudes towards viewing of female sexual ecstasy on mainstream TV. No longer will the sight of a woman climaxing carry a stigma equivalent to Jacqui Smith's husband's penchant for "additional features".

But to the bearers of Mary Whitehouse's torch the decision is one more blow to broadcasting standards, particularly as it came just days after two broadcasting committees announced the rules might be relaxed to allow the promotion of abortion services and the showing of condom ads before the 9pm watershed.

"I think it is very odd for C4 to take this decision when the consultation on advertising condoms and abortion services is ongoing," said chair of Mediawatch UK, John Beyer. "I understand its plight – advertising revenue is down so there is a pressure on the channel to accept this kind of campaign. But they must remember, they are public service broadcasters – they can't just ignore the fact that many people may find this offensive."

So does the ASA's endorsement of the female orgasm mark the start of a more honest and liberated representation of female sexuality? Or does the stylised way in which the women are portrayed make it just another perceived ideal for women to aspire to? And do advertisers and broadcasters have a responsibility to shield adolescents from such images – or to open their eyes to the realities of sexual relationships?

The sense of unease attached to the female orgasm has its roots – somewhat inevitably – with the repressed Victorians. So distressed were they at the thought of women enjoying the sexual act, the gynaecologist, Isaac Baker Brown and the distinguished endocrinologist, Charles Brown-Squard advocated clitoridectomy to discourage women from the filthy habit of touching themselves down there. Female circumcision continued to be widespread in parts of Europe long after Baker Brown was discredited and persists today in some African countries.

In the 1970s, US feminist Shere Hite tried to debunk some of the myths attached to female sexuality – and received such hostile press she felt she had to flee to Germany.

But in the past few decades, the orgasm has become a familiar feature of films and edgier dramas. There is a plethora of The Sex Inspector-type programmes, which not only film people in the throes of passion but analyse their performance and discuss ways of heightening their enjoyment in the future.

Such is the scale of the debauchery in C4's Shameless that it would be easy for a female orgasm to pass unnoticed, or for it to be confused with matriarch Mimi having one of her hissy fits.

Of course, sex has long been used to sell products from deodorant and cars. And the female orgasm is frequently hinted at: the woman in the Herbal Essence adverts seems to have an awful lot of fun for someone who is washing her hair; and whatever Sophie Dahl was up to in the banned Opium billboard poster, it wasn't knitting. As far back as 2001, Coco de Mer – the chain of sex shops launched by Anita Roddick's daughter Sam – used photos of 11 "real" women having "real" orgasms as part of an advertising campaign, without provoking huge outrage.

On the slightly more prudish BBC and in the world of TV advertising, however, full-blown female orgasms are still few and far between. But isn't it time we grew up and stopped treating sexual pleasure as something either to be ashamed of or to be sniggered at?

Dr Tuppy Owen, chair of the Coalition for Sexual Freedom, thinks so. She welcomes the Durex advert as a sign of a growing acceptance that sexuality is a positive part of human existence. "I think it's very good that Durex are acknowledging the pleasure of sex," she said. "It has previously promoted condoms as strictly for family planning purposes. It wouldn't even enter the Aids debate, so this is fantastic."

Owens believes the kind of images the advert presents will do much to wipe away the shame some people still attach to sex.

"A lot of people are shielded from discussions about sex especially if they are stuck at home because they are disabled or they're in an uptight environment and being able to see that having an orgasm is pleasurable might stop them feeling guilty about sex," she says.

When it comes to adolescents, though, the debate is more complex, with experts divided over whether or not exposing young people to sexual images makes them more or less likely to engage in risky or promiscuous behaviour. For parents worried their children are being exposed to too much too soon – through explicit pop videos, websites and reality TV shows – giving a sexually explicit ad the thumbs up for pre-11pm viewing might seem a step too far.

Sex and relationship expert Dr Petra Boynton believes the Durex advert – which uses sex to sell a sex product – is less potentially damaging than those which use it to sell, say, cars, and that it could provide an interesting talking point for parents.

"To be honest, if a young child came across this advert, it would probably go over their heads – they might think the women were singing," she said. "And it might be enough to tell older ones the women are happy. But you could use it as a starting point for a discussion about the pleasure sex can bring – and I don't think that would be a bad thing at all."

But how genuinely representative of female sexual enjoyment is the Durex ad? The women who feature in it are, of course, all beautiful and stylish and when they climax – on black satin sheets, in the bath, their hands pressed against a window – their hair and clothes are unruffled, their make-up unsmudged. Their faces aren't even flushed as a result of their exertions.

"The problem is that the ad is very stylised," says Boynton. "It shows a particular way women are supposed to look when they reach orgasm – but not everyone does look like that so it becomes something else for young people to worry about.

"Other images show women making a lot of noise. As an agony aunt I have young people contacting me and saying: 'She wasn't screaming, she was very quiet – what am I doing wrong?' So if you were talking to young people about the ad, you would have to make it clear, it isn't always going to be like this."

Despite Boynton's reservations about its accuracy, the Durex ad does seem to highlight increased female empowerment and a shift in the gender power balance. Because as the female orgasm takes on a new acceptability, the male orgasm is fading from sight.

When it does appear – at that start of American Beauty, for example, where Kevin Spacey's character masturbates in the shower – it is often used to illustrate inadequacy rather than virility.

And most adverts currently trading on men's sexuality do so in a way that sends it up, like the one for microwavable burgers that has the tagline "what can you do in 60 seconds?"

"At the moment people want to look at women," Owen says. "Men are worried about looking at images of other men and getting turned on, whereas there is not the same taboo about lesbianism."

So the Durex Play O TV ads may be heralded as controversial, challenging or iconoclastic. But the day the company promotes a product using a montage of men reaching climax to the Match Of The Day theme tune – well, that really will break new ground.

The science bit

When a woman becomes sexually aroused her heart beats quicker, pumping blood to her muscles. Her breasts enlarge and nipples become erect. Her face may become flushed as adrenaline dilates the body's superficial blood vessels, and her clitoris enlarges. In the brain the activity of neurons increase in certain areas, in the lungs breathing becomes quicker, to oxygenate blood.

Blood rushes to the pelvic area creating a natural lubricant which makes sex smoother.

When she climaxes, blood pressure and heart rate continue to rise. In the vagina she'll feel rhythmic contractions as the muscles suck semen higher into the vagina, making it easier for sperm to fertilise an egg. These pulses happen about once every second. Mild orgasms have three to five pulses, intense ones 10 to 15.

A poll of best movie orgasms found the Meg Ryan fake from When Harry Met Sally was only second. The survey by website yesbutnobutyes.com said top honours went to Shirley MacLaine who, in Being There, pleasures herself while her husband (Peter Sellars) watches television. Number three was Madeleine Kahn in Young Frankenstein, whose hair turns white after experiencing the monster's "schwanstucker". Other contenders included Dennis Hopper in Blue Velvet, Gina Davis in Thelma And Louise and Jane Fonda in Barbarella.