It was the lads' mags – with semi-naked women in suggestive poses on their covers – being sold at eye level at her corner shop that did it.

"I just don't think I should have to look at that – it's degrading," said 17-year-old Isabella Woolford Diaz. "If people want to buy it, fine, but I don't think 11-year-old pupils should have to look at it."

Deciding to take the matter into her own hands, the student formed a feminist group at Camden school for girls, and before long a core group of 15 teenagers – boys and girls – were attending. "I was getting so frustrated at how women were portrayed and I wondered if I was just being pernickety," she said. "But I soon realised it wasn't just me."

The group is one of dozens of new feminist organisations springing up around the UK, according to the campaign group UK Feminista. Research carried out to mark the group's second birthday has revealed that the number of active grassroots feminist organisations has doubled in the past two years.

These are feminists who do not fit easily into stereotypical moulds: young and old, men and women, urbanites and country dwellers. A new breed of feminists is starting to rise up.

"It's a really exciting time. We are seeing a real resurgence in feminist activism that is moving from the margins to the mainstream," said Kat Banyard, founder of UK Feminista and author of The Equality Illusion. "People are willing to put up their hand and say they are a feminist without the fear of being ridiculed. Particularly in the past 12 months, we are seeing people standing up and willing to be counted." Like the Camden group's members, many of them are young, passionate and unafraid to take direct action.

Anna van Heeswijk, from the campaign group Object, told of a group of year 10 students from an inner-city school she had spoken to about the sexual objectification of women. The students went to their local supermarket to protest against the sale of lads' mags at eye level. They were armed with banners, horns and slogans, and before the end of the day the manager had agreed to order "modesty" covers to obscure the sexualised images of women.

"A new generation of young women across the country are sick and tired of being sexualised, objectified and trivialised," she said. "There is real power in the voices of these young women. This is a good moment for feminist activism. The tide is turning." For decades, activists have questioned whether men can be feminists, but according to campaigners men are now swelling the ranks.

Matt McCormack Evans, who founded the Anti Porn Men Project while a student at Hull University, believes more men want to become involved in the fight for gender equality and more women are willing to accept them.

"Things have really changed over the past few years, and it is becoming much more acceptable for men to challenge traditional ideas about masculinity," he said. "Lots of younger feminists want men to be involved and aren't so wary of them taking over – no one wants to see a feminist movement run by men. This is a movement with aims and goals, not a club with gatekeepers."

New groups are popping up in the most remote places. Campaigners can be found in practically every area of Britain – even the Orkney Feminist Network has 40 followers on Twitter. Michael Moore, the regional organiser for UK Feminista in Northern Ireland, said sites such as Twitter and Facebook had enabled people in even the most remote parts of the UK to tap into the debate. "Now it's as easy as sending an email to mobilise people. There's no apologies, no minutes – people can engage and thrash out issues in an online space immediately. It's really sped up the power to communicate."

Recent debate over issues such as Nadine Dorries's proposed bill for compulsory lessons on sexual abstinence for teenage girls and fears about a growing anti-abortion climate in the UK have put feminism right back on the news agenda.

And recent high-profile events, such as a series of "SlutWalks" to protest about the treatment of rape victims, have seen feminists back on the street.

As 17-year-old Nina Mega from Edinburgh put it: "Sometimes you get the idea that the world is a pretty misogynistic place and feminists are few and far between, but when you see all those like-minded people together – men and women – you just think: 'Wow.'"

Every one of their number will be needed, according to campaigners who argue that women face a barrage of challenges not seen for a generation.

With twice as many women as men expected to lose their jobs in the public sector, women hit hardest by services and benefits cuts and concerns that as state services shrink women will have to fill in the gaps, women may find hard-won gains in sexual equality are rolled back, according to the Fawcett Society.

"We are at a watershed moment for women's rights," said Anna Bird, acting chief executive of the Fawcett Society. "Women are feeling the brunt of cuts and job losses. Instead of seeing progress in women's rights we could see the pay gap between women and men widening. We can't be complacent and I think a growing number of women are aware of that."

Q&A with Kat Banyard, founder of UK Feminista

Why is feminism an 'unfinished revolution'?

While there have been enormous advances for women, many legal rights – like equal pay – are yet to become reality. Women are outnumbered four to one in parliament, women working full-time are paid on average 15% less than men, and two-thirds of low-paid workers are women. Hard-won gains – like the right to a safe, legal abortion – are under attack. And new manifestations of sexism – like the global sex industry – have put progress into reverse.

How are protests today different from the first wave of feminism?

Clearly some aspects have changed. Take technology: advances in communications technology mean social networking sites are now key mobilising tools and feminists can instantly report and broadcast footage from their own protests. Or take economics: three decades of neoliberalism have led protest targets to follow the shift of power from government to private hands. But the fundamentals of feminist activism remain the same: a struggle against privilege and profit, stretching from the bedroom to the boardroom. And, as ever, the promise of feminism is a world that will be better for all.

How can budding feminists start their own 'revolution'?

Whether it's Hugh Hefner's toxic brand of sexism, cosmetic surgery supremo Mel Braham's phoney solution to women's lack of body confidence, or the coalition's cuts to women's financial independence, you have the power to take them on. Whoever you are, wherever you are, there is something you can do. So choose your target, get organised, and get taking action.