Jeffreys, a revolutionary lesbian feminist, is pursuing her 30-odd-year mission to shift women out of their collective complacency. Beauty And Misogyny is her sixth book. Like the others, its central theme is an exploration of the use of sexuality by men to dominate women. Much of it is spent arguing that beauty practices - from make-up to breast implants - should be redefined as harmful cultural practices, rather than being seen as a liberating choice.

Jeffreys' introduction to feminist campaigning began in the early 70s when she joined a socialist feminist group (she was later thrown out for suggesting men were to blame for the oppression of women). Sandra McNeill, who met Jeffreys in that group, remembers her as "the Andrea Dworkin of the UK. She was, and still is, seen as an extreme, man-hating feminist". Dworkin, as it happens, lived with a man, whom in 1998 she married.

Not Jeffreys. She became a lesbian in 1973 because she felt it contradictory to give "her most precious energies to a man" when she was thoroughly committed to a women's revolution. Six years later, she went further and wrote, with others, a pamphlet entitled Love Your Enemy? The Debate Between Heterosexual Feminism And Political Lesbianism. In it, feminists who sleep with men are described as collaborating with the enemy. It caused a huge ruction in the women's movement, and is still cited as an example of early separatists "going way too far".

"We do think," it said, "that all feminists can and should be lesbians. Our definition of a political lesbian is a woman-identified woman who does not fuck men. It does not mean compulsory sexual activity with women." Although many of the more radical feminists agreed, most went wild at being told they were "counter-revolutionary".

Jeffreys' brusque manner and her seeming conviction that she is 100% right when discussing her topics of interest have led to accusations of arrogance from fans and critics alike. Although a funny and charismatic speaker, she can irritate those who feel they are being dictated to. However, she can be generous with her time, particularly with young women new to the movement.

Jeffreys sees sexuality as the basis of the oppression of women by men, in much the same way as Marx saw capitalism as the scourge of the working class. This unwavering belief has made her many enemies. Postmodern theorist Judith Halberstam once said, "If Sheila Jeffreys did not exist, Camille Paglia would have had to invent her."

In Jeffreys' latest book, she questions why the beauty industry is expanding, and why liberal feminists should see a virtue in women having the power to choose practices that a few years back were condemned as oppressive. The critique of beauty practices, written about by Dworkin in Women Hating, in 1974, has today all but disappeared, making way for procedures that "break skin and spill blood".

The history of the beauty industry is threaded through the book. Cosmetics have been used to alter appearance for thousands of years, sometimes exclusively by prostitutes and others deemed disreputable, other times as a political gesture. The suffragettes fought for the right to look and dress as they saw fit, some wearing red lipstick as a symbol of feminine defiance. After the second world war, a shortage of men meant that women tried hard to look as attractive as possible in the hope of getting a husband, and make-up became, Jeffreys argues, "a requirement that women could not escape, rather than a sign of liberation".

Born in 1948 into a working-class family from the East End of London - though her parents were based at an army camp in Munster at the time - Jeffreys, who has been teaching international gender politics at the University of Melbourne since 1991, describes herself as a product of the postwar sexual revolution. Going from an all-girls grammar school to Manchester University in the late 1960s, she expected the intellectual atmosphere of Left Bank cafes. What she found instead was young men sitting around the students' union bar making smutty jokes. She sank into a depression that lasted several years.

During this time, she started sleeping around with men, considering it her "duty" to be liberated and progressive. This was the start of her interest in the politics of the sexual revolution, which was to result in her book Anticlimax: A Feminist Perspective On The Sexual Revolution (1990), in which she argues that newly achieved and much-vaunted sexual freedom did not constitute any real gain for women, but continued their oppression in another guise.

After university, while teaching at a girls' boarding school in 1972, she read Kate Millet's Sexual Politics, a groundbreaking analysis of female oppression and patriarchy. She became "enraged" at what she learned about men's abuse and control of women.

"My rage has never gone away," she says now. "I am grateful for that." She says she distinctly remembers the moment she realised, during a conversation about politics with a man, that he was seeing her merely as a woman, and therefore inferior. "I was furious. He actually said I had the brain of a man, and while in the past I would have been flattered, a dam had burst and everything became clear." While many of her generation of radical feminists have given up fighting, Jeffreys' passion has not abated.

Her books have a common theme, whether she is writing about Victorian feminism, the sexual revolution of the 1960s, "queer" sexual politics or the history of prostitution. As Jeffreys puts it, "Male supremacy is centred on the act of sexual intercourse, justified by heterosexual practice." For her, heterosexual sex is sexual desire that eroticises power differences. Lesbian and gay sexual practices do not escape her scrutiny. Two of her books, The Lesbian Heresy (1993) and Unpacking Queer Politics (2003), focus on how "queer" sexual politics have led to oppressed sexual minorities embracing any kind of sex, such as sadomasochism, in the name of liberation.

Jeffreys tends to see things coming before they happen. She was the one who warned, in the early 1980s, that pornography and sadomasochistic sexual practices would invade the lesbian community. They did. She predicted a global trend to call for the legalisation of prostitution. There was.

The idea that radical feminism was a phenomenon of the 1970s exasperates her: "The media always look for the 'new sexy feminism' that will enable them to put young women in sexy clothing on their pages who rail against man-haters and hairy-legged dykes, and say how much they love porn. This began in the 1980s, when the 'femme cult' got under way." She's referring to the likes of American writer Katie Roiphe, author of The Morning After: Sex, Fear And Feminism On Campus (1993), who argued that feminism has made victims of women and created a culture in which men are given "mixed messages" regarding sex, resulting in unfair accusations of "date rape".

In return, Jeffreys has been treated with hostility and ridicule. Pornographers named a dildo after her - The Sheila: A Spinster's Best Friend. Sexual libertarians are infuriated by her criticism of the practices they enjoy. When she pointed out in Anticlimax the need for feminists to challenge the dominance and submission characteristic of many a heterosexual relationship, she was pretty much a lone voice, and still is. Feminist Sheila Rowbotham said in response that she had abandoned attempts at equal relationships because "equality is not sexy". Author Bea Campbell considers Jeffreys "too full of intense rage, and deeply pessimistic about both men and women. She presents a political perspective that means there is no possibility of change".

Others oppose Jeffreys' position in a more general way. Natasha Walter, author of The New Feminism (1999), for example, argues that today's women do not want their behaviour "policed by feminism", but wish to enjoy sex with men, wear make-up, and dress in short skirts and high heels without feeling they are betraying feminism.

But Jeffreys' critics can get her wrong. It is precisely because she considers that the personal is political that she presents hope of fundamental change. She believes that, ultimately, true mutuality and equality between the sexes are possible, but they are dependent on every woman resisting the status quo and critically examining her life choices. Men, she argues, would be forced to change if women did.

Jeffreys' journey that culminated in Beauty And Misogyny began when she decided, in 1973, to abandon both heterosexuality and her feminine appearance. "I gave up beauty practices, supported by the strength of thousands of heterosexual and lesbian women around me who were also rejecting them. I stopped dying my hair 'mid-golden sable' and cut it short. I stopped wearing make-up. I stopped wearing high heels and, eventually, gave up skirts. I stopped shaving my armpits and legs."

The book is one she has wanted to write for years, as "liberal feminists and postmodernists" challenge the early feminist critique of beauty practices. "Not only are the practices creeping back, they are becoming more severe and invasive of the body itself," she says.

She has taken on a tough battle: the cosmetics industry is bigger than ever (in Brazil, for example, there are more Avon ladies than members of the armed forces). And she has taken on broader targets, too. The sex industry, the misogyny of fashion, what she calls the "mutilation" of transgender surgery and the dangers of sexual libertarianism are all seen by Jeffreys as intrinsically linked to the beauty industry.

In the chapter on cosmetic surgery, she looks at the growing pressure on women to conform to models of femininity derived directly from the sex industry, such as having trimmed labia and Brazilian waxed pubic hair. "Men's desire for bigger and bigger breasts, and clothes commonly associated with prostitution, has resulted from the mass consumption of pornography."

Jeffreys can always be relied upon to back up her arguments by unearthing facts that are both disturbing and hard to believe. She cites one example of a porn actor who sold bits of her genitals to "fans" over the internet after a labiaplasty operation. She points to studies that have found significantly higher rates of suicide among women who have had breast implants. The latest, conducted in 2003 by the International Epidemiology Institute of Rockville and funded by Dow Corning Corp, a former maker of silicone gel breast implants, included a study of 2,166 women, some of whom received implants as long as 30 years ago. Dow Corning also funded an earlier Swedish study, which examined 3,521 women with implants, and found the suicide rate to be three times higher than normal.

There are other unwanted effects. Nipples can lose sensation and, in extreme cases, rot and fall off; stomach stapling can cause severe swelling in the pubic area; and liposuction can leave a patient in serious pain. A number of women have died after surgery, while others have been left in permanent discomfort.

Jeffreys argues that many male fashion designers are "projecting their misogyny on to the bodies of women", and gives examples of collections featuring images based on sexual violence - Alexander McQueen's show for his masters degree was entitled Jack The Ripper, and depicted bloodied images of Victorian prostitutes. A later show in 1995, Highland Rape, featured staggering, half-naked, brutalised models. And John Galliano, in his 2003 collection for Christian Dior, Hard Core Romance, used the imagery of sadomasochism, putting his models in seven-inch heels and rubber suits "so tight they had to use copious amounts of talcum powder to fit into them".

"One notable difference in fashion shows in the past 10 years is that the models are required to show more and more of their bodies," says Jeffreys. "Some are posed to look as though they are about to engage in fellatio. Pole dancing is now a staple of some fashion events."

For Jeffreys, the last thing women should be doing once they achieve a semblance of choice is returning to practices imposed on them during darker periods. After the US invasion of Afghanistan, for example, beauty clinics opened up all over the country, offering cosmetics as an antidote to the enforced wearing of the burka. "You'd have thought the women would have had other things to worry about," she sighs.

She likens cosmetic surgery such as labiaplasty and breast implants to female genital mutilation. She concedes the distinction that genital mutilation is carried out on children who have no choice in the matter, "but the liberal view of choice, which is that women can now 'choose' to engage in harmful, oppressive actions, does not make the practice of slicing up women's genitals to please men any less vile". As Jeffreys points out, hymen repair surgery, which is available through the public health service in the Netherlands, is sought not only by women whose cultures require them to be virgins when they marry, but also by western women whose partners wish to penetrate a tighter vagina.

Jeffreys unearthed some frightening facts - for example, a Home Office paper claiming that BSE can be transmitted through beauty products because many contain bits of dead animal. Breast implants can contain brain, fat, placenta and spleen. A link between hair dye and bladder cancer was discovered in a US study of 3,000 women who use such products regularly, and formaldehyde, found in nail polish, shampoos and hair-growth preparations, has been outlawed in Sweden and Japan, with the EU allowing its use only in small, regulated quantities.

There is much evidence that children are being targeted by the beauty industry. Kiss Products, a cosmetic retailer, has joined forces with Disney to promote lip gloss and nail polish kits through licensed animated characters. Proctor & Gamble is looking to market its Cover Girl cosmetic range to eight- to 10-year-old girls by making the use of make-up resemble game playing. "It is not only the cosmetic industry that is recruiting young customers," says Jeffreys. "It is becoming more common for young women from affluent families to be given breast implants for their 18th birthday."

Again, she blames the fashion industry. "Some designers are using 12-year-old girls in shows because their bodies are perfect to show off the type of clothing being peddled at the moment. Many men are sexually excited by this look, and the industry exploits this." Parisian designer Stella Cadente used models as young as nine in her 2001 show; it was reported that they wore "plunging necklines and high hemlines". And, Jeffreys points out, Cadente is not alone in using child models in the world of fashion.

There is little, if any, feminist critique of men's cross-dressing, but in Beauty And Misogyny Jeffreys provides a unique analysis of what she describes as "men adopting the behaviours of a subordinate group in order to enjoy the sexual satisfaction of masochism". She says we need look no further than transvestite pornography, with titles such as Enforced Femininity and Forced To Grow Breasts, to understand how femininity and womanhood have been developed to ensure that women are seen as different and less powerful.

Jeffreys maintains that transsexual surgery is an extension of the beauty industry offering cosmetic solutions to deeper rooted problems. She argues that in a society in which there was no such thing as gender, there would be no need to undergo such surgery.

Jeffreys offers no comfort zone for her readers. Unlike some feminist theorists, she refuses to couch her arguments in inaccessible, academic language, or to accept that feminism has achieved its aims. For Jeffreys, the word "complicated" does not exist. The reason for women's oppression is horribly simple: men want their power and, for that reason, they will keep women in a state of subordination to maintain it. She tells me she will never give up. "I cannot imagine living without a purpose of changing the world for the better. It gives life meaning. It is more urgent now than ever. No liberation is possible for women in a world in which inequality is sexy."

· Beauty And Misogyny: Harmful Cultural Practices In The West, by Sheila Jeffreys, is published in paperback by Routledge at £12.95.