Romala Garai had them tittering at the Bafta awards, two months after she had given birth. She told a bad-taste joke: “I had the misfortune of having 23 stitches in my vagina. So I didn’t think I’d be laughing at anything for a long time. But tonight’s nominees have proved me wrong.” Few feminists laughed with her then. But having a baby daughter, it seems, nudged Garai towards feminist politics. She is a versatile and winning actress and also gorgeous, which shouldn’t matter but does, in all female careers. Though she appears in the Fifties TV drama The Hour wearing tight, alluring clothes and much red lipstick, she has joined the crusade against misogynistic men’s magazines and the supermarkets that sell them. This week “Lose the Lads’ Mags” campaigners are going after Tesco.

I back these sisters unconditionally. I, too, am revolted by Nuts and Zoo and other such rags which celebrate coarse, rough manhood. But I wonder if the protesters are being myopic or naive or disingenuous. Garai’s own life choices reveal the conscious and unconscious ways women collude with sexism, sometimes for self-promotion, sometimes because they can’t fight the cultural pressures and imperatives of modernity. She admits: “I have been part of the problem. Let me now be part of the solution.”

She wants her daughter to grow up in world where females are not demeaned. Amen to that. So do millions of other women and men. But the problem now is not just sicko men wanting to leer at female bodies or watching hard porn and sometimes acting out violent fantasies. It also includes those women who are up for all that, too, in their heads and some in real life.

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Female porn models and performers are not new. They have always been around. A woman, Pauline Réage (real name Anne Desclos), penned that hard SM novel Story of O (1954), about a woman whipped, branded, pierced and raped into willing submission. The Sixties sex romp Emmanuelle was also written by a woman, Emmanuelle Arsan. The porn business would have died long ago without female participation. When we railed against the industry in the Sixties and Seventies we never addressed these inconvenient truths. Now that the pornification of society is so pervasive and deep, we have to deal with the many ways in which women support the evil, rather than fighting it.

The shabby and trashy Fifty Shades of Grey is soon to be a film. Directed by Sam Taylor-Wood, a woman. Such liberation, say fans, shows how women now own porn. Like hell it does. It just confirms that women have completely capitulated to the forces of darkness. What is erotic about a virgin graduate, groomed into sexual compliance and controlled by a filthy rich businessman? The campaigners against lads’ mags never got together to condemn that trilogy, which was read by millions of young women who now think it is cool and sexy to be handcuffed and beaten by an overpowering male.

And little is ever said about the grotesquely sexist women’s magazines in which female bodies are turned to meat and the sexual content is as coarse as in publications for randy men. Our daughters are caught up in this sexist whirlpool and most can’t fight the currents.

Then there is internet porn, which churns out the most depraved and dislocated sexual acts and is watched compulsively by millions, not all of them men. The number of women addicts to the hard-porn sites is growing exponentially and they, too, are getting desensitised, watching and wanting more violence, finding satisfaction and relationships ever more difficult. The Quit Porn Addiction counselling service had no female clients in 2009. Now one in three are female.

The psychotherapist Phillip Hodson has noticed the shift: “Traditionally, women’s voices have been against porn, which is seen as a male thing.” That is no longer the case. Women use it to have sex, quickly and easily, without emotional investment. He doesn’t think we should get too het up about the emerging phenomenon. I think we should. To focus on male porn habits and not females taking up the habit is perverse.

We know through serious research that there is a subtle but real connection between the objectification of women and violence against women. Tomorrow, the Green Party MP Caroline Lucas is hosting a meeting in Parliament where Polly Neate, chief executive of Women’s Aid, will present some alarming statistics showing how younger women now are more likely than older women to be victims of domestic and sexual violence.

She and others have long argued that hidden and overt media sexism and porn can drive men to hurt and abuse girls and women. But without addressing the role played by women in this story, they are repeating the mistakes we older feminists made in the Seventies and Eighties. On this issue – though men must bear the larger responsibility for where we are today – women cannot avoid blame and claim innocence and helplessness.

Reproaching blokes and campaigning against sexism in the media and on the internet is vital. But to clean up our world, women need to be honest about their complicity. Female editors, advertising professionals, models, actors, media CEOs and, most of all, consumers, could together defeat the pernicious spread of porn. They just choose not to.

y.alibhai-brown@independent.co.uk