This summer I found myself bursting for a pee at Notting Hill Carnival, gazing enviously at the banks of corrugated iron that had been set up for blokes to tiddle behind for free. I looked more balefully at the hour-long queues snaking out of houses and flats where anxious-looking women paid £2 and hopped desperately from foot to foot.
On the other side of the street, there was a group of 10 or 12 young women, four of whom were holding a picnic-blanket-sized scarf up against a wall in order that the others might relieve themselves behind it. I'm not embarrassed to say that I ducked in and saved £2 while spending a penny. There was much eye-rolling among the scarf-holders at the men by the nearby council-issue pissoir. "We can look after ourselves anyway," one of the women said. There were a couple of rotations in shifts; I held the scarf up for a few others, and then its owner folded it up and put it back in her bag.
When the cluster of women disbanded, I was amazed to see that they didn't even know each other. I had assumed they were a group of friends out for a day together, but we all split off in our twos and threes. We had just got together because we had been able to make each other's life a bit easier, just for five minutes, just because we all needed a wee. If that isn't sisterhood, I don't know what is.
It's female nature to overcome difficulties as a community, be it making the tea or getting the vote. It's what we've always been good at, thanks to our supposedly more "emotionally cogent" brains and our shared sense of purpose. And it's a central theme in the new film Made in Dagenham, out on Friday, which celebrates 30 years of the Equal Pay Act. It starts at the very beginning of the road to financial equality – with the 187 female machinists who went on strike at Ford's Dagenham plant in 1968, insisting that their status and pay cheques as "unskilled" workers be changed to match those of the men at the same factory. Their three-week-long industrial action upset colleagues, friends, husbands, trade unions and politicians, but they held together and didn't stop until they met with minister Barbara Castle and thrashed out a deal to be paid 92 per cent of the male rate, hastening the introduction of equal-pay laws two years on.
"How have you coped?" a journalist asks the machinists as they arrive at Whitehall in the film. "We're women," replies Sally Hawkins, who plays ringleader Rita O'Grady. "Now don't ask such stupid questions."
The notion of "the sisterhood" – that is, the empowerment of women that comes from a sense of solidarity and community between them – is a hangover from what is known as the "second wave" of feminism in the 1970s, when women's groups were set up to discuss the problems, the travails, the glass ceilings and the brick walls that the movement was trying to smash through. By the end of the decade, however, these groups were felt to be rather self-righteous and po-faced, even puritanical. And today, you might expect the very concept to sound clichéd, indulgent, even excessive, to a younger generation of women who – like me – don't necessarily experience overt inequality in their everyday existence.
But the Sisterhood is alive and well, not to mention relevant, and it's flourishing among young women right now, as they find new ways of creating and strengthening female communities.
"I can see a return to sisterhood in many walks of life, from the Orange Prize to Harriet Harman supporting Diane Abbott's bid for the Labour leadership," says Natasha Walter, the campaigner and author of Living Dolls: the Return of Sexism. "It's about working together even though we are all different. Women are constantly encouraged to compete between themselves and to snipe at other women, but there can be something really life-changing about building this sense of solidarity." Until recently, women have been tribalised – young versus old, fat against thin, the rich squaring up to the poor. But something has happened, especially among young women in the past few years. There is new sense of community.
"Many of us are united in the need to recognise the obstacles we face as women, and give each other leeway and support because of them," says Holly Combe, a writer for the website The F-Word. "But an important part of working together is being able to disagree with each other without this being held up as evidence that 'women are bitches'."
These days, unmarried women without children are, to some extent, in the unique position of not having to think all that much about gender. Not if we don't want to, anyway: we are told from a young age that we can do anything we want, and our exam results bear witness to that. My male boss doesn't hand me his coat and hat when he gets into the office; I don't even have to make sure I get the scrag ends when I cook for my boyfriend. On the rare occasions that I do cook for him, that is. My existence is not that of a second-rate citizen; it has not been characterised by struggle. So why would I want to sit around talking about being a woman when I can just get on with living as one?
But today's sisterhood of young women hardly conforms to the stereotype of campfire songs, dungarees and buzz-cuts; it has blossomed on the internet, on blogs and social-networking sites like Twitter and Facebook. It has found its feet in a recession that has hit women hard and a climate of spending cuts that seem to target female interest. The revival of the sisterhood has happened against a backdrop of unfaithful footballers and a celebrity-worshipping culture, various elements of which are calibrated to pit women against each other. Women of my age – in their mid-twenties – were teenagers in the Loaded and FHM era, but we also grew up with the Spice Girls, who preached mates before dates.
"When I was young, there was something left over from the Fifties," says The Independent's agony aunt Virginia Ironside. "A feeling that without a man, a woman was nothing. You wouldn't be upset if your friends broke off plans with you for a date, because everything stopped for men. You'd expect this would have made the links between women stronger, but it didn't because it meant that any relationship you had with a woman was very easily broken. Now there is definitely less emphasis on men."
That comes of course from cultural change and development, the simple fact of girls growing up with expectations equal to those of boys – but the importance of women to each other has been further enhanced by the agency given to individuals by online message boards and women's websites. The media has always been a prime target for the women's movement to get its message out there. In the beginning there was Spare Rib, these days there is Jezebel, Bust, the feminist webzine BitchBuzz and jezebel.com.
"The internet has been vital to the growth of this new feminist movement," says Kristin Aune, co-author of Reclaiming the F Word. "Today, feminist communities are virtual as well as local or issue-based. But that doesn't mean modern feminism is individualistic – people may be sitting alone in their bedrooms, but they're making friends and connections with other feminists online at the same time."
In addition to making acquaintances, there is the opportunity to have your say. From petitioning sexist companies and advertising to flagging up flagrant Photoshopping in fashion magazines, every issue becomes a potential stand to be made.
One of this year's most successful female websites has been Ihollaback.org, a blog where women can catalogue their experiences of street harrassment. It started in New York in 2005 and is now an international phenomenon, having set up in most cities across the States, as well as in London this summer. "When harrassment happens, you're often alone," explains its executive director Emily May.
"It can be very isolating and Hollaback turns it into something shareable. We build awareness and a community. Women have always made change by telling their stories – well, the net has changed the game. It's the new campfire, the new place to tell your stories. Women don't put up with harrassment at home or at work, why should we put up with it in the streets? We're aiming to create a global conversation on a king-sized platform."
It's astonishing the difference solidarity can make. At the end of the Seventies, the culture of women's groups and sisterhood died out because of radicalism and schisms within the movement; in the Eighties, there came a backlash against feminism and against women, which resounded well into the Nineties through "lads' mags" and the rise of the "ladettes", and on into the Noughties with WAG culture and skimpy swimwear on MTV – all of which cast women as archetypal competitors and encouraged jealousy and gendered sniping. "Traditional gender roles have tended to pitch women against each other," adds Holly Combe. "I think we become less vulnerable to such divisive tactics if we accept that women are not all the same. I reckon that's an important part of 'sisterhood'."
Lately though, the cultural tone of the debate has changed and women's input has soared. Unsurprisingly, when it's women espousing the views themselves, the conversation becomes much less fraught with infighting. It is only recently that we have come to see the power of the online commentator, as women's sites are taken more seriously and the importance of the internet in terms of trend-setting becomes incontrovertible. Women now have the opportunity to be vocal once again; we are strongest when we are act together, and we have found ourselves in another era of female success and strength – thanks to the power of the new sisterhood.
And what vibrant and highly visible celebrations there have been of it. There are dozens of successful young female recording artists working beyond the normal, namby realms of honeyed popstrels, from Ellie Goulding and Florence Welch to Katy Perry and Lady Gaga; there has been an infiltration of Hollywood, with films like Juno, written by ex-stripper Diablo Cody, and Made in Dagenham chronicling one of the most important moments in female history; and the introduction of the Orange prize has established female writers within the literary hierarchy.
It comes at a point at which the power and pervasiveness of the sex industry is unparalleled, when there are strip clubs opening on provincial high streets and more 2,000 women have become victims of sex trafficking in the UK this year alone. It comes after gunman Raoul Moat tried to kill his girlfriend for cheating on him, after revelation upon revelation of footballers sleeping with escorts rather than their wives. It comes after a prostitute winds up on a reality TV show, and she is the person decried for moral bankruptcy. It comes at exactly the time we need it most. Back in the Seventies, there were the Pussycats, a group of anti-women's lib women, who believed "the lamb chop is better than the karate chop"; nowadays we have the Pussycat Dolls, suggesting that most men wish their girlfriends were as attractive as they are.
"It's important that sisterhood is seen as a positive thing," says Natasha Walter, "lending support to women, rather than as a negative thing, withdrawing support from men. Because there has to be solidarity with men too, if we are to build a more equal future."