Like so many things that men have been doing for longer than anybody can remember, it only looks weird when women start to do it. Women are tentatively – which is to say, in small numbers, not in attitude – embracing single-sex socialising. At the end of last year, Kate Percival launched Grace Belgravia, a women-only members club in central London. (I have just learned online that the club's name is meant to represent the three graces: charm, beauty and creativity. They omitted to mention this when I spoke to them, perhaps judiciously.) There is already The Sorority in Holborn, with the same ground rules (men only as guests, on certain nights, and only if they behave). Later this month, KC Gates, a fascinating Canadian rugby player, plans to turn Soho bar Sofakingcool into a women-only restaurant.

About 20 years ago, so-called "gentlemen's clubs" (indicating that they excluded women only as part of a larger agenda of excluding anyone they didn't go to school with) looked like the dinosaurs of clubbing – large, maladroit and maladapted, facing hostility all around, and not long for this world. Through a series of manoeuvres that mainly centred on improving the food, they have pulled through. Rupert Lendrum, the secretary of Buck's Club (PG Wodehouse modeled Drones on it, if you're interested in that sort of thing), modestly underlines that his isn't the only establishment that's thriving. "All the clubs in London, as far as I'm aware, are doing well. The appeal these places have - Whites, Turf, Brooks, that sort of thing – well, clearly there is an element that people like the aura of tradition, which a lot of us do in all walks of life. But along with that, the clubs themselves have upgraded the ways they deal with all sorts of things, whether that's the kitchen or the bar or the administration." The one thing few of them have upgraded is their policy on women, but as it transpires, that was only ever a problem for the people on the outside.

So, let's say women are launching members' spaces of their own in the spirit of haven't-beaten-them-may-as-well-join-them: that, as a business proposition, would be reasonable enough. Emulating gentlemen's clubs doesn't seem remotely the point, however. A spokesperson for Grace Belgravia explained: "This is a thinking woman's club. Men's clubs were out-of-the-spotlight places, where men could get together, play cards, drink and eat to their hearts' content, talk about business and the things men talk about. What we are building is totally different – it's a sorority for women." What does this mean, exactly? A lot of it, dispiritingly, is about healthy eating. I know – years and years of fighting over equality, contraception, work, pay, smashing the patriarchy, and we are still eating raw food for pleasure and having spa treatments. It makes no sense, but it's pointless to dwell. "We have an alcohol licence," Grace's person on the ground puts in. "But," I helpfully clarify, "women don't come here to get rat-arsed without all the hassle from him indoors?" "No, no, no."

It's more that this, however – there's also a lot of emphasis on networking. It's such a curious concept, that you might need a single-sex space to disinhibit you from the pain of making human connections, but Daisy Buchanan, the 27-year-old scenester, part of Awesome Women of Twitter (AWOT), explained. "I know I'm being stupidly heteronormative, but even if you don't go out to meet guys, it's always going to be on someone's agenda. It's weirdly relaxing for that pressure to be off, and suddenly you can meet people and have conversations and swap numbers and it feels like there's less of an agenda. In London, it's quite unusual to make new friends – you stick with the people you were at college with. I think that's because, when you meet someone and say, 'Let's be pals', in mixed company, that seems weird."

This is quite different from the old boy networks, who all know each other anyway. The idea seems much more classless when women do it, and people have been toying with it for some years. Jonathan Downey, who runs the Player and Milk & Honey in London, said he wanted to start an all-female members bar 10 years ago, but struggled to find a female business partner, and didn't want to front it himself for a thousand obvious reasons. He says, in gleeful contradiction of what everybody else says, "It was more a no-men club, rather than female-only. For me, the idea would be 70% networky, just meeting and talking to other women. Then 30% would maybe be an element of bicuriosity … I've had a nice time in straight bars that have had a strong gay following. I've had a nice time in bars where there's a sense that anything might happen. There needed to be an element of sex, like there would be with any bar. But it would be so subtle you wouldn't even necessarily notice. And that's why it was really important not to do it in Soho, where it would immediately be billed as a hangout for lesbytarians. It should have been City-fringe, Clerkenwell, places full of professional women who are out there, doing stuff. There must be places like this in New York or LA."

Most probably there are, but in the US, the most famous enterprise of this sort is Beso in Las Vegas, run by Eva Longoria of Desperate Housewives. It has two USPs, besides its policy of excluding men – catwalk shows and "small plates". Small bloody plates. Everyone mentions them – in Grace, you can choose on the menu between a "little", a "little more" and a "lot". Even KC Gates, who I think of more as embodying a fourth grace (awesomeness), says: "It's all tapas and hummus. There's a lot of women in London nowadays who are looking for a place to eat when they've been to the gym, or have something in their stomach when they drink." It is taken as given across the piece that a main-sized main course is too much for women, just another weapon of oppression in the arsenal of the patriarchy. I don't really accept this principle. But don't let me and my mansize appetite get in the way of all this appealing zest for business.

KC Gates is interesting on the subject of her new restaurant's identity – she doesn't want it to be a "lesbian" bar at all, even though she namechecks the Candybar a lot as a role model ("we'll have men at designated times, and in certain amounts – the Candybar lets in one man for every three women, so we may do it like that") and Sofakingcool is gay(ish) at the moment. "I want all women to come down – stagettes, women from different cultures, Muslim women, all women." Is that really going to happen, though? "Well, a lot of men from different cultures I've met have said, yes, they would love a place where their wives could come and they know they're not going to be hit on." Here I nearly gag on my cow pie. You're setting up a place where men know their wives aren't going to be hit on? "Look," she says pleasantly, "I would love a place where women could come and not be harassed or bothered by the opposite sex, or even the same sex. A place where women can come, they can eat good food, they can network … I've worked security as a doorman. I've worked different clubs, lesbian and straight, and got a sense of what women want. Often they want a drink with the girls and then to go on and meet a mixed crowd."

This point dovetails exactly with that of Grace, even though the two institutions are about the farthest apart in atmosphere of any here mentioned – it's not so much about men and women, as about celibacy. The absence of sex, even in bursts so short that you can measure them out in coffee spoons, creates a breathing space in which other things – fellowship, calm, creativity, portions that are too small – can flourish.

And many women who said they would consider single-sex restaurants or clubs say that the inspiration comes from spaces that are all-female by accident, or over time, or by coincidence: book groups; all-female gyms; women-only chat forums. The pioneers of this, especially on the internet – Sali Hughes's Facebook community, the Awesome Women of Twitter – used the originality of their endeavour as a chance to do something different, rather than abide by old norms. In those groups it makes perfect sense, and it makes sense therefore that some of those women would want to experiment with evicting men from meatspace as well as cyberspace (some evenings – not all the time).

None of this is to be confused with the classic men-only/women-only, stag/hen style event, where it's not the opposite sex that's banned, so much as known members of the opposite sex, who have clothes on. Men have never had any trouble distinguishing between the need for a single-sex social space for the purposes of going to a strip club, or whatever, and the need for one that's for sitting around talking about those "things men talk about". With women, conversely, there always seems to be this ambiguity about what the purpose is of excluding men. Is it so they can see the Chippendales? Is it really just a gay bar that isn't calling itself a gay bar? Are they going to start primal screaming or talking about healing? Everybody associated with these new ventures uses the word "professional" to distinguish the type of women they're talking about, and thereby the type of activity, even though there is nothing to stop a bunch of lawyers from wanting to see men in pants do synchronised dancing; even when they're talking about stay-at-home mothers, who are the opposite of professionals (that's not a value judgment, by the way – I'm not ruling out their having been professionals or being professionals in the future). While normally I'd be on red alert for a class subtext, I don't think that's what the word denotes, here, even when restaurant owner Downey uses it in open contrast to the "cattle crowd" – ("I'm talking about the professional crowd, not the cattle crowd") – rather, the tag is about the mood and inhibition level of the group, and is actually pretty accurate, if a bit roundabout. There's behavior you might associate with a hen crowd, or a stag crowd for that matter, that you wouldn't exhibit in front of work people, whatever kind of job you have. Noise is just part of it, but it's perhaps the part that the rest of the world notices the most. Downey continued, "I don't think anything can control or keep the noise down on a hen party. We've tried it and nothing seems to make a difference … "

There is, in conclusion, probably as much difference between these single-sex establishments as there is between them and regular bars. I don't think single-sex socialising is the shape of things to come; but I think it's a shape we'll be getting more used to.