Tony Ray is making cards with toddlers Lizzie, Alex and Maya – none of them his own. Gary Collins is comforting James, whose dad has just popped out to feed the meter. Rufus is playing with the dolls' house, and Joe, Violet and Barnaby are creating a den. It's Friday morning at Dads and Littl'uns, the bi-weekly playgroup in Wimbledon, set up and run by dads.

More fathers are taking responsibility for childcare. Traditional roles are changing and, from necessity or preference, fathers are taking flexible working hours, spending more time with their children and adopting the role of primary carers.

"This is post-feminist gender disorder," says Robert Bagley, father of three-year-old Lizzie. "Following the women's movement of the Seventies and Eighties, women have moved into senior positions in the workplace and become high wage earners. Many men have wives with good salaries who carry them at home so they can be full or part-time home dads."

Two little girls who made a beeline for the fancy dress rack, are dancing about as fairies. Others are on the trampoline. Boys are shoving cars and buggies across the floor. Peter Balderstone is standing with his back to the children counting to 20 in a booming voice as toddlers scurry off to hide. Robert is stirring coffee, other fathers are chatting about last night's football match. There isn't a woman in sight.

"We welcome mums," says David Carr, who has taken over as organiser. "And we arrange events for the whole family, but this is a primarily a place for dads." And fathers have come from near and far.

Peter has travelled from Notting Hill Gate. "I go to women's groups locally but here we talk about more interesting things! Last week we were discussing late Marxist theory. Mothers' groups are fine but there can be a lot of carers and au pairs, who form different groups with different kinds of support."

Now in its eighth year, Dads and Little'uns has no institutional connections and is not beholden to any organisation. Men pay £3 per session and £4 if they come twice. There are sessions every Monday and Friday morning from 10am to noon and some fathers bring a packed lunch and stay until 1pm. There are social functions once a week, a football team and outings in the summer. The group stays open in the holidays when children need entertaining most; some members have moved away and formed groups in Dulwich and Exeter. The baton of organiser passes from father to father as the children grow up and new men join.

The founding fathers set up the group because most playgroups were run by mothers for mothers. "Mothers form relationships before their babies are born, at antenatal groups and in the hospital," says Robert. "The relationships continue when the children are born and become toddlers. Fathers who stay at home have none of that support. Mothers' groups welcome them but the bonds are different when dads get together."

Some fathers have part-time jobs in industry, teaching, the arts and media. They've discovered that being a home-based father can be a mixed blessing; it can be boring, monotonous and repetitive. There can be tensions too as mothers feel they are missing out. Peter says his wife would definitely prefer to bring up their daughter: "The traditional route would have worked fine for us. Of course, we could change our lifestyle and move somewhere else but to afford our house, one of us has to earn a good salary. I always knew I would be the main carer and I like it as it is. My wife's work maintains the life we want to live collectively. She thinks I'm the more cheerful and optimistic one and this is good for our daughter Scarlett. But she does feel regret."

Robert agrees: "My wife is happy to know Lizzie is looked after by me but she also wants to be at home. She feels the need to perform the traditional role at the weekend. I love cooking. She doesn't. On Saturdays she rearranges the kitchen, I put everything back again on Monday."

Ideally, most couples would like to share childminding: "We're all driven by money and few men have the luxury to opt to be full-time dads," says Gary. "And when you've been a home dad for a few years, it's difficult to get back into the workplace. You need to network and you can't do that looking after children."

As a full-time father, you can feel a lack of control because you are not earning. It can be frustrating and isolating. Martin Eason believes that, if it weren't for the group, he might have been more inclined to want to go back to work. "But economically we're better off than if we hired a full-time carer, and it's definitely rewarding spending time with the children."

"You miss a lot by going out to work," Andrew Lawford confirms. "You gain a lot by being with the children. You have time and the freedom to see the changing seasons. Sometimes when I worked full-time, a year would pass and I'd realise I hadn't even noticed we'd gone from winter to summer and back again."

Mark Chester, family officer with Liverpool Football Club and chairman of Who Let the Dads Out?, a Christian organisation that runs a string of fathers' groups, has seen a huge change in attitude and opportunity for fathers, since the group began in Chester in 2003: "Dads' toddler groups didn't exist then. The Community Church parent and toddler group wanted to give mums a break and get dads involved."

One Saturday morning, 23 fathers turned up at the church hall with their children: "This was very unusual. It showed there was a need and desire for this kind of group. As a result we ran monthly Saturday dads' playgroups, which still continue today."

Mark began doing antenatal work with fathers-to-be, exploring the emotional aspects of fatherhood. "Having a baby is a shock for everyone. There is less social life, less sex life, less money and less time with your partner or wife. Men can experience negative feelings. We looked at how they felt and the changes that were likely to occur in their lives."

He carried out a survey with a small group of fathers to assess their satisfaction levels. "Generally, men's satisfaction was lower [than women's] when the children were babies, though they were happy to be fathers. When the youngest child reached four or five, men's satisfaction began to improve. Our aim was to encourage dads to stick with it because the benefits are there in the long run."

Mark feels that there has always been a willingness in men to become involved in caring for their children, "but over the last few years there has been a change in opportunity and in society's expectations".

Today there are 21 groups registered on the Who Let the Dads Out? website.

Adrienne Burgess, the head of research at the Fatherhood Institute, confirms that over the last 30 years there has been a rapid increase in the time men spend with their children. Time spent with children has risen by more than 800 per cent and fathers are far more likely to look after children on their own. Fathers take on about a quarter of parental childcare and this goes up to one-third when mothers work full-time. "In the past, there was no need for this because mothers were at home doing it all. Now, half the mothers of children under the age of one are in the paid workforce."

Work has also become more flexible: more fathers work from home and this leads to more sharing of childcare. Research shows that children who have a close and positive relationship with fathers as well as mothers, whether they live together or not, have more empathy and form more positive friendships; they are less likely to commit crimes or get into trouble with the police; they are happier and do better at school.

"The importance of the father's role is now recognised right from the beginning," Adrienne continues. "Couples are more stable when both partners are sharing. The role of childminder isn't a glamorous one but it has many advantages: it promotes patience and makes individuals more aware."

Men who have been involved with their children from an early age are likely to have grown emotionally: "These are pioneering fathers, creating a space for dads and children, where it is the norm for dads to be involved. It can be very invigorating and empowering because they get to see other fathers benefiting too. The more skilled the men become at looking after the children, the more rewarding it is."

Back at Dads and Littl'uns, it's time to start packing up. Paul, who is here for the first time, has a happy smile on his face. "I'm disorientated," he says. "I'm used to being the only guy with a group of women. Sometimes the single mums want to flirt with you. This is refreshing and safe."

"You have male company but the common factor is the children," says Paul Rawbottom, an early member of the group, whose children have now moved on to school but who still comes regularly to the sessions. "The group fulfils the role of teamwork, which you find in the workplace but lose when you become a full-time parent."

Teamwork is definitely in action now as everyone helps stack tables and chairs, wash coffee cups and clear the hall. It's obvious the children are happy and the fathers are, too. And if that's the case, the mothers must surely be happy as well.

Fathers' playgroups: Tips for success

* Keep the group relaxed and with few formalities – the dads are the group.

* Serve good refreshments: you need fresh coffee and a large cafetière. At Who Let the Dads Out? there's a giant grilling machine for making bacon butties.

* Arrange social functions once a week such as drinks in the pub; it doesn't matter whether two or 22 dads turn up.

* Organise a football team and matches.

* Arrange family events and outings in the summer.

* Stay open in the holidays, when children need entertaining most.

* Keep the website up-to-date to attract more dads.

Some benefits of an all-dads group:

* Same-sex conversations tend to be more relaxed, though you can have good conversations with women, too.

* Women are more competitive about child development. They talk a lot about what their children can do and achieve.

* Blokes talk about blokes' stuff: music, football, beer, women, politics, technology.

* Women form bonds through antenatal clinics, giving birth and breastfeeding. Men just stick a bottle in the baby's mouth. Mums have less of a need to let you into the circle.

* Everyone has a vested interest in helping to run the group.