Should we all be stopping at two? A report in July by the Optimum Population Trust – a British think-tank dedicated to reducing population growth and its effects on the world -- argues that families should restrict themselves to two children, because it is no longer responsible, or environmentally friendly, to bring three, four or more into the world. According to John Guillebaud, co-chairman of the Manchester-based think-tank and an international family-planning expert, a voluntary stop-at-two guideline would allow couples to choose a greener lifestyle. And while the report says that the annual net rise of 300,000 in Britain's overall population has several components, including immigration, it believes that reducing the number of children in each family would send a signal to the rest of the world that we want to consume fewer of the earth's resources.

So what is the outlook for big families? Rosamund McDougall, a member of the trust's advisory council, says there is no suggestion that Britain should adopt such coercive measures as China's controversial one-child policy. But with 669,531 babies born in England and Wales last year and the birthrate running at a 26-year high of 1.87 children per woman, she says everybody must realise that there are long-term implications in having lots of offspring. "People think it's all about eco-nappies and hand-me-downs, but it's not quite as simple as that," McDougall says. "You've got to consider the environmental impact across the 80 years that each of these babies is likely to live. We've calculated that each UK child is going to cost the world the equivalent of 620 return flights between London and New York across a lifetime." And then, of course, many of these children will have children of their own.

How, then, do couples who have chosen to have big families react? Do they fear becoming modern-day pariahs, or do they believe they can defend their choice?

Many friends and acquaintances thought the Russel Fisher family was already complete a dozen years ago -- there already was Toby, twins Alexandra and Hugo, and Matthew -- when Jo announced another pregnancy and went on to produce Douglas, now 12, and, three years later, Myles, now nine. "Some people were a bit shocked when they heard I was having yet another baby," admits Jo, age 51. "I'm a nurse and I think there was a bit of a sense of, she's a medical person so doesn't she know what's causing it? But on the whole people have been shocked by the practical side of what we've taken on in having a big family, rather than disapproving of it from a moral point of view."

To her, the Optimum Population Trust's report sounds "more than a bit dictatorial". Who, she asks, do they think they are, telling people like her and her husband, Jamie, 52, that they shouldn't have six children? "If we had 13 kids and were asking the state to bring them up, perhaps it would be different," she says. "But we're not asking anyone else to feed them or clothe them.

"I think we're having to conform to narrower and narrower norms in this country, and it's a shame. There are plenty of people around who choose to have no children at all, which surely opens the possibility for people like me to choose to have more than two."

In many ways, life in the Russel Fisher household sounds like an antidote to the oft-lamented excesses of childhood in Britain today. "When you've got a lot of children, you don't have as much money as other families," says Jamie. "They can't be indulged in the same way, and they can't be pandered to in the same way. Our children know how to cook and use the washing machine and iron their clothes and change the plugs -- they've got to! We all pitch in, all the time, because life in a household with lots of people requires everyone to play their part."

Finances are a constant challenge. "When the children were little it was tough -- I worked right through my pregnancies, and I went back to work when they were quite young, albeit part-time," says Jo. "Once there were three we knew that paying for their education would be out, and we've never had a family holiday overseas. Most years we borrow a friend's cottage somewhere and all squeeze in."

Jo also admits: "I do need to escape sometimes. I can't stand that 'Where are you, where are you?' the whole time. I do find it quite difficult to find time for me -- I'm very good at telling patients to do that, and not so good at doing it for myself."

She says she and Jamie are "definitely not planning types" and she believes that mothers of many children tend not to be the controlling sort: you simply can't control that many kids. She admits cheerily that she lives surrounded by domestic clutter, and loathes housework.

What she and Jamie share is a huge sense of enjoyment from their children and their family. The highlight of the week is Sunday afternoon, when the clan gathers for a meal (Toby, the eldest at 22, has left the family home in south London for his own flat in north London, while Alexandra, 20, is away at university). The best day they've had recently was Jamie's birthday, when everyone came home for a Sunday brunch. "It was wonderful," says Jo. "We had Buck's fizz and I put the food on proper serving plates so there was a real sense of occasion, and everyone was chatting and enjoying one another's company -- and you do get a huge sense of what fun it all is, and how lucky we all are to have one another."

Jamie says: "Having the family around me are the best times. It's the nicest thing in my life."

Hugo, who is 20 and Alexandra's twin, says he finds it "a huge comfort" to come from such a big family. "You know you're never going to be on your own, that if you need something there will always be someone you can turn to," he says. "It can be quite challenging in terms of getting on with people -- I have easier relationships with some of my siblings than with others -- but then again, because there are so many of us, things are less intense.

"Most of the people I meet come from families with one or two kids and they're often astonished when I tell them about mine," he says. "But if they come and have a meal with us, you can tell they're really fascinated and they like us -- there's all this stuff going on, it's so busy and there's a lot of fun and banter." Does he resent the fact that his friends from smaller families might have more financial help from their parents than he has? "I don't, actually," he says. "I think what I've got is a more realistic approach to money. We've never been the kind of family where a child could just say, ‘I want something’ and then get it. We've had to earn our treats."

Materially, many of Hugo's friends have more than he has, and they have travelled. "I think, I've got years ahead of me to go travelling," he says. "You don't have to have seen the world by the time you're 20."

They grow their own vegetables, they compost their waste, they're avid freecyclers, most of their clothes are second-hand and, to reduce their carbon footprint, they don't drive anywhere on Fridays. In almost every way, the Corbets are a model green family in England: there's just one caveat. "We've got five kids," says Angie -- Martyn, 19, Mike, 17, twins James and Jo, 14, and Sarah, 12. "And as far as some people are concerned, that completely negates everything else you do to reduce your impact on the planet's resources."

Angie, who is 48, resents the fact that she's persona non grata in the green circles around her home in Wimborne, Dorset. "Much more significant to me is the fact that we're bringing up five young people who will be productive members of society and will play a part in alleviating problems rather than causing them.

"I think the green argument is lopsided: I can see that the human race has grown too much, but I feel when people reach a certain level of education they tend to choose to have fewer children. And since that means some people in our society are choosing to have fewer than two per couple, that means there's the scope for some people to have more."

To Angie, what matters is "making the best of the resources we've got". In big families, there is a natural tendency, she argues, to green living: her family lives so frugally, she maintains, that they probably aren't using up any more of the earth's resources than a more profligate family with just two kids.

"When you tell people you've got five they sometimes say, 'Blimey, haven't you got a television?' You occasionally get people who are a bit critical, but they tend to be coming from the social rather than the environmental end of things. They tend to assume you can't be a good parent to that many children; you can't look after them effectively. The truth is that things can go wrong in small families and things can go wrong in big families, although when they go wrong in big families people are maybe more inclined to point their fingers and blame it all on that."

Angie, who works part-time for a sheltered-housing scheme, says she and her husband Peter didn't plan to have so many children. "We might have stopped at three, but the third pregnancy was twins and then we thought it would be nice to go on and have one more. I'm not so much into babies, but I love having older children. I feel I'm making a really positive contribution to the 21st century by bringing up these wonderful people who are going to live through it."

For Yvonne Pascal, a mother of eight, it's simplistic to say couples should stop at two children because it's best for society. "How can anyone know that?" she asks. "In my family, my third child and my sixth child both want to be doctors. If we'd stopped at two, those two children, who may very well go on to be wonderful doctors, would never have existed.

"The thing about our world is it's not just about numbers, it's about how you use your resources. I'd say a family like mine, which is 10 of us living on a fairly tight rein and being economical and careful and not wasteful, is not bad for the environment. Living in a big family means making a lot of compromises and sacrifices and often big families like mine turn out well-rounded people who become the most useful members of society. I got my kids' reports recently and they were all really positive; they're all caring kids who are motivated and want to make a difference. The world is a better place for them, for all of them!"

Yvonne, 42 -- whose children range in age from four to 24 -- works full-time. When she talks to customers at Debenham's department store on London’s Oxford Street, where she works, "their jaws drop" when they hear about her large family. "Having lots of children these days is very unusual, and I guess people think it's even more unusual to be working as well, especially as my youngest is only four." There's a lot to fit in, she adds, "but I'm really happy with my life".

Yvonne and her husband, Clavan, 46, had their first child when she was 17; over the years, seven more followed. "We didn't plan it, and we didn't not plan it," says Yvonne. "We just thought we'd see what happened, and this was what happened."

Their eldest, Nadine, is now 24; behind her come Natalie, 20; Nathanael, 15; Naomi, 12; Neiel, 11; Naarah, eight, Noah, six, and four-year-old Noelani. "I always wanted my first daughter to be called Nadine, and she thought of the name Natalie for her sister. And I wanted my first son to be called Nathanael. So when the next baby came along we thought, we'd better find something beginning with an N or that one will get a complex. And so the N tradition was born: they've all got middle names with different initials, so the post doesn't get mixed up."

Yvonne says she doesn't feel people are critical of the fact that she's got so many children. Her formula for managing things is "being incredibly well organised. We have definite routines in our house: bedtime for the younger ones is eight, and that's a house rule. It's not negotiable. All the children live at home, so there are 10 of us in a six-bedroom house, and I'm very clear about the fact that they all have their jobs to do and they all have to muck in.

"Even the little ones have small jobs, like emptying the small bins and sweeping up under the table after mealtimes. And the older ones take responsibility for things like making everyone's packed lunch in the morning -- even I get my lunch made for me!

"There are times when getting everything organised is a bit like a military operation: on Sunday mornings, for example, the whole lot of us go to church -- usually it's eight of us in our people-carrier, and the two big girls following on the bus. And getting us all ready and out of the house is some feat." But they always get there, she says.

She believes each side of her life contributes to the other: "I learn things in my career as a manager that I can put into practice in my home life, and I learn things as a mother that I can use as a manager," she says. Having so many children "gives you so many experiences -- you go through so much".

But is there -- can there possibly be -- any time for just her, or for her and Clavan? She says there is. "I do have whole days when I just slob out and wear my tracksuit and don't put on any makeup. And the children know that, and they respect it. They know I need some time to chill out." Sometimes Clavan picks her up from work in the car "and we use the 45-minute journey home to enjoy being on our own together and to talk. It's really precious."

She thinks her baby-producing days are over: "The hospital worried about me a bit in my last two pregnancies because I'd had so many babies, but I was always very healthy and everything was fine." But she's not putting the idea of another completely behind her. "I'd be surprised if I got pregnant again but I wouldn't be horrified -- I'd cope with it," she says. "But now Noelani has started school it is quite nice not having any pre-schoolers. I have had 23 years of them."

How do the children feel about being one among so many? Nathanael says he's never felt he doesn't get enough attention. "I know my parents love me, but I also know there are younger kids in my family and they need more taking care of than I do. And I know I have to help take care of them. I'm not sure I'll have as many children as my parents have, but I think it's a great experience to grow up in a big family. I think it makes you more grown up and independent."