IT was the late poet Philip Larkin who famously claimed sexual intercourse began in 1963 - "Between the end of the Chatterley ban/And the Beatles' first LP".

Technically, it was always a suspect assertion. Sexual intercourse had been going on in Britain, one imagines, for at least few thousand years before. But there's a truth in there too. Because it's the moment that the British legal system decided it was actually OK for your wife (or your servants, for that matter) to read DH Lawrence's novel; that all the alpha males of fiction - Updike, Roth, Amis, McEwan - began to write candidly about sex and desire from the male viewpoint.

So the question is: where are the women? When are they going to be allowed to write about sex and sexuality as easily and freely as men?

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Well, maybe the answer is now. In the last few weeks I have read two books written by women, which both began by raising the subject of masturbation. In one, Viv Albertine's candid, potent memoir Clothes Clothes Clothes Music Music Music Boys Boys Boys, the author said that she never masturbated. In the other, Caitlin Moran's fizzy, filthy roman a clef, How To Build A Girl, her teenage character very definitely does. Some 45 years after Philip Roth's novel Portnoy's Complaint, women in books are pleasuring themselves too (liver is not involved, though).

There are other indicators. The other night while in Tesco I noticed that the supermarket was selling Helen Walsh's novel The Lemon Grove, the story of an older woman (in her 40s) having an affair with her stepdaughter's teenage boyfriend, a book that includes an anal sex scene between the couple. The book is also concerned with age, class and culture of course (you could say the same with Moran's and Albertine's), but it's the book's candour about female desire that has given it heat.

There's more. Also recently published is Daily Telegraph columnist Bryony Gordon's The Wrong Knickers - an account of her wild twentysomething years ("wines, lines, fags and shags" as one reviewer summarised it) and, just out in paperback, Katherine Angel's part memoir, part poem, part essay Unmastered, whose subtitle - A Book On Desire, Most Difficult To Tell - gives you a sense of what it entails: "When he handles me, it's a shock," she writes at one point, "a deep, juddering pleasure, a ferry's heavy murmur."

There's a term in urban geography used to describe the paths that people create for themselves rather than walk the designated footways provided by town planners. Desire lines are those paths created by people on foot. Lines of choice rather than lines that come with official approval. Maybe the desire line in women's literature has now been marked in. We have arrived at a point where women writing about desire is accepted and even encouraged, and in turn where female sexuality is no longer hidden away or frowned upon.

Or have we? After all, isn't Helen Walsh constantly being labelled a "literary bad girl"? (A tongue-in-cheek designation, perhaps, but was Philip Roth ever called a literary bad boy?) And wasn't there a recent controvery involving allegations that Michael Fallon, a Conservative MP, who has since been made a minister, had referred to Gordon as "that slut?" (He has denied using that term.) So, is female sexual desire - when it makes an appearance in literature, or life for that matter - still seen as problematic, or even shameful?

"I do think women are asked to perform a certain kind of personhood where you can justify your beliefs or your desires or your actions or your sexual choices," Katherine Angel tells me when I ask her just that. "In so many forms of writing or conversations about these things there's an implicit demand that you justify what you do or you justify your physical pleasures. It seems to me that's the completely wrong way round of thinking about these things."

Angel is an academic by trade, a fellow at Queen Mary University in London. When she started writing Unmastered - originally published in 2012 - she says she felt she was almost writing in a vacuum. But she adds: "I did have a lot of conversations about things that I was thinking about potentially for the book and my sense was that there was some kind of hunger for something that hadn't been done or said. It's not that I'm saying anything revolutionary. I'm putting on the page certain ideas, certain feelings and shining a light on them and saying, 'It's important'."

The "it" in question includes how desire at times challenges feminist thought or demands that it's rewritten; desire, Angel argues, can be ambivalent, sexuality can even be perverse. And that is normal. So why is it a problem if women address these things when no-one raises an eyebrow when men do?

"There are certain things that if a woman says them, they seem shocking," Angel continues. "They also seem to endanger the woman. A lot of response I get to my writing is a kind of amazement that I took the risk of writing in that kind of voice and writing frankly about things that are usually behind closed doors. There's a sense that women have much more to lose when they write in this way, when they reveal the complexity and messiness of their lives and the strangeness of their sexuality. And I do think it's not quite the same for men.

"For male writers there's much less sense that they have made themselves vulnerable. We seem to think that women's sexuality is at odds with their status as people and it's precisely that issue I try to point to in my writing. That's my feminist battle; to say, 'Why do we allow women such a narrow space in which to move, not just sexually but as people? Why is it more risky for women to write about messy, complex things than it is for men? That's not right'."

And yet it goes on. "I'm getting lots of letters from disgruntled readers," Walsh admits when I call her at home on the Wirral. But it's not so much the sex in The Lemon Grove that seems to be the problem. "It's the fact that there's this incredulity that a 17-year-old boy could find a 40-year-old woman attractive."

It's possible that there speak people who haven't been 17-year-old boys, of course (I remember being more interested in Mrs Robinson than Katherine Ross when I was watching The Graduate around that age.) Or it could be that we are now in an era that is more sensitive to age differences between sexual partners with the inevitable questions of trust and its potential abuse. Walsh, though, believes any such sensitivities are gender-weighted.

"Women are subject to stricter and more gendered codes of behaviour, especially where desire and sexuality are concerned. It's endearing to be vulnerable and a little bit ditzy in fiction, but we don't want our female characters too gutsy or slutty. The idea of a middle-aged women with her less than perfect middle-aged body, masturbating and lusting after a teenager is anathema to most. On the other hand, the idea of a 90-year-old man lusting after a pubescent girl (as in Gabriel Garcia Marquez's My Melancholy Whores) is deeply profound."

There is nothing new about women writing about sex. Anais Nin and Pauline Reage may be the most frequently dropped names, but in the 1970s Erica Jong immortalised the phrase "the zipless f***" in her 1973 novel Fear Of Flying. In the 1980s we had bonkbusters such as Shirley Conran's Lace, though when it was originally published it didn't include the word "masturbation" to accord with the publisher's wishes (though it did include that scene with the goldfish). More recently the likes of Jeanette Winterson and Sarah Walters have written explicitly and openly about female sexuality. Coincidentally, after reading Walsh's book I found a copy of an old Nell Dunn novel, Tear His Head Off His Shoulders, in a secondhand bookshop. Originally published in 1974 ("And he opened up the bedclothes and he pulled me under him and made love to me so fiercely that I gasped, gasped and yelled, yelled so loud I knew even the neighbours would hear…") it is at least as frank as as any of the recently published books I mentioned at the top of the page. So what's new?

Intentionality perhaps. Nin and Reage, author of The Story Of O, were writing explicitly - in both senses of the word - for men. Their writings are deliberately pornographic. Winterson and Walters's starting point is, of course, gay sexuality.

So have we arrived at a point where Moran, Walsh, Angel and the others addressing the subject of desire have, by their sheer number, normalised writing about desire, in a way that is not pornographic but which situates sexuality within our lives and lifestyles, that sees it as part of all of our personal stories; something that shapes who we are? And if so, does that matter?

I think it might. And that's mostly because of another book we haven't yet mentioned: EL James's 50 Shades Of Grey. Only last week social media got all hot and bothered about the release of a trailer for Sam Taylor-Wood's film version of the "mommyporn" book that has sold upwards of 100 million copies. Film critics even reviewed it.

The first thing to say about the book is that it at the very least indicates there is a desire to read about desire, and that some of the Puritan shame that surrounds the subject in Britain and America has dissipated. Men and women were happy to openly read the book on trains, planes and buses (forget the anonymity of Kindle; at the height of the 50 Shades phenomenon I was seeing plenty of EL James paperbacks on my daily commute to Glasgow).

Any closer reading of the book also suggests that what would once have been called deviant sexuality - which in 50 Shades amounts to mild S&M - has now entered the mainstream, taking its place alongside Ann Summers high-street stores and sex-toy reviews in women's magazines. Again you can see this as shamelessness replacing shamefulness.

This is not necessarily a step forward. "From one angle - 'Women are allowed to have kinky fun too' - you can see it as liberatory," Angel points out. "But from another angle you can see it as the rhetorical arm of the sex-toy industry and a very consumerist conception of desire where you can buy more stuff to make you more sexually successful."

In magazines like Cosmopolitan, she argues, that co-option of a "kinky sexuality" is focused on "the very traditional end" of marrying someone and having babies. "I think you can see 50 Shades in that structure. It's kinky but ultimately the man will save you and buy you stuff."

In this sense the shamelessness is, in its own way, conservative. We live now in a world flooded with pornography. It is only ever a mouse-click away. "It's very important to make the distinction between pornography and sex," says Angel, "but at the same time those things are constantly bleeding into one another and are hard to delineate. Because so much of sexual desire is fantasy."

The problem with that is pornography is so masculine, at times even brutally misogynist. So how do you write about sex in a world in which the very language we use is couched in that particular register of maleness?

"It makes it very difficult, especially when you're dealing with a young person's sexuality," admits Walsh. "I've got a 17-year-old boy in there who's been brought up on the codes of pornography. That was a problem in the first draft - how to write about sex honestly."

And even if you do there's always the danger that you end up nominated in the annual Bad Sex Awards (such a very British response. Giggling puritan prurience. Where are the Good Sex Awards, one wonders?) Some people might suggest, then, that you don't write about it at all. If it's a challenge to write convincingly, why not keep it behind closed doors? Why not go for abstinence?

But that seems perverse in its own way. Why would you not want to write about such a central facet of human behaviour? And there's another reason to write about it, surely. If the code of pornography is now the first language of sexuality in the culture, shouldn't we be trying to learn another language? Shouldn't women, in particular, be able to write about their experiences as a corrective to the juvenile, sometimes violent fantasies that pornography offers?

In a world where pornography is ever-present, don't we need people - and women especially - to write about what sex is really like? About its pleasures and failings, about the part fantasy plays and the importance of choice and responsibility in a world that is dominated by men (and not just in a Christian Grey manner).

Talking about How To Build A Girl, Caitlin Moran recently said: "I wanted to write something warm and funny and real about a girl going out into the world and meeting men, feeling desire and wanting pleasure, and realising that the two most powerful things a girl can say are yes and no - and how both are just as important and joyful as each other."

That seems a noble goal to me. Maybe what we need is more - good - writing about sex and desire. But as we said at the beginning, maybe things are changing. Remember, it was not Gordon but Fallon whose alleged behaviour was criticised when the "slut" claims emerged the other week.

Walsh's book has been critically acclaimed and thousands of women and a few men have recently cheered on Moran's effervescent, sex-friendly feminism during a national tour in support of How To Build A Girl.

"I think to have a book with an anal sex scene between a 17-year-old boy and a 44-year-old woman as a talking point in the aisles of Tesco, Asda and Sainsburys is saying something about where we are," laughs Walsh.

Equal between the covers, finally?