Chris Goodings went to the Glastonbury music festival a couple of years ago to sell his green wares but made so little money that it did not even cover his costs. This year was different. Trade has been buoyant everywhere. “Awareness has shot up,” he says. “There were 10 times as many people coming to see us. They used to say, ‘How does it work?’ Now they’re asking for particular products because their friends have them.”

Last week Goodings, who sells and installs renewable energy through the Solar Energy Alliance, was at the Big Green Gathering, an eco-festival held at Compton Martin near Bristol, which ends today.

It began as a Glastonbury spin-off 12 years ago but has attracted record numbers of visitors this year as climate change and energy policy emerge as mainstream issues. It is rumoured that David Cameron, “green” leader of the Tory party, might still turn up.

The event takes place just days after Tony Blair and Arnold Schwarzenegger, the governor of California, signed an agreement on climate and clean energy issues and Currys, the electrical retailer, announced plans to sell solar panels.

With the possible exception of budget airlines, just about everybody these days subscribes to values hitherto regarded as strictly eco-fringe. The Conservative party, whose environmental adviser, Zac Goldsmith, was on the bill at the BGG, has been joined by big corporations in embracing green imperatives.

How does this affect ordinary people? Currys says that buying and installing enough panels to generate 50% of an average three-bedroom household’s electricity will cost about £9,000. That is not as expensive as digging a borehole for ground source heating (even modest systems cost as much as £15,000), but it does rather suggest that only the rich can afford to be green.

Goodings confirms that most people to whom he sells turbines and solar panels are seriously prosperous: “With 80% of my customers, when I arrive I expect to see a swimming pool to the left and a tennis court on the right.”

Despite the large sums of money required, Goodings insists that one of the main reasons why people want renewable energy is financial: “We don’t talk about saving the planet. We talk about saving money over the long term. The eco-warriors all believe in renewable energy but they can’t afford it.”

The Big Green Gathering was founded in 1994 by Andrew Oubridge, known to everybody as Brig, a veteran of green gatherings since the 1970s. This festival is different from others because there is no advertising; and with bins everywhere for visitors to sort their rubbish by type, the organisers hope to improve on last year’s 46% recycling record, nearly three times the national domestic average.

Hugo Charlton, a barrister, considers the Big Green Gathering to be, essentially, a little Eden: “This is a different world. It’s how it ought to be. No litter, no fast food.”

Critics of the green movement have always regarded it as unappealingly self-denying. Few would object violently to the absence of advertising or litter but Sam Willitts, from Brighton, who was here for the first time, had obviously had enough of the food: rice, chick peas and veggie burgers.

The Lunnon family, who were selling their ice-cream made locally on their farm, were a little surprised to find an absence of mains electricity. (Other stalls had brought along their own renewable energy solutions, including turbines and solar panels.) In keeping with the organiser’s request that visitors consider the environmental cost of travel, Charlton had driven here in a car powered by liquid petroleum gas. Two other visitors became instant celebrities when they revealed that they had walked to Somerset from Cambridge.

What is on offer on the green future’s front line? Prue Hardwick, who runs a bed and breakfast in the Midlands (“with organic mattresses”), says the BGG is a great opportunity for people concerned about climate change and energy to come together: “It’s quite easy for the rest of the time to get depressed and think that nobody cares. But when you come here you see that people are doing things. You go home feeling inspired.”

I point out that the crowd contains a disproportionately large number of people in lurid tie-dye outfits, goatee beards and dreadlocks. Might these alienate the mainstream? “It is a kind of tribal gathering,” Hardwick concedes, “but it’s not excluding. There are all sorts of people here. I’m from ‘middle England’ myself.”

The idea that environmental issues are about “them and us” has gone, says Avril Evans, who co-ordinated the area devoted to sustainable living. “It may have been like that in the past but now people in the alternative movement know they can’t just build a little eco-village and keep themselves to themselves. They have to be part of the wider community.”

Evans lives with her family in a development of 12 low-impact homes in Somerset. James Ross, her boyfriend, builds timber-framed homes and other buildings. Like Goodings, he gets much of his work from rich clients: Ross is building a barn, using medieval techniques, that will cost a small fortune.

However, most people at the Big Green Gathering reject the idea that only rich people can be green. “This is not about owning the latest technology,” says Evans. “It’s about changing attitudes and habits. There are a lot of things you can do that are very simple.”

Rod Hall, who recently retired as a university lecturer, says the problem lies precisely in people’s desire to buy increasing amounts of energy intensive kit. It would be better, he says, if many of these items — often used infrequently, such as lawn mowers — were shared. Another problem that Hall says could be remedied cheaply is the waste of purified drinking water on flushing lavatories. “Collecting rainwater should be made a statutory requirement in building regulations,” he says.

This kind of earnest discussion is everywhere. You hear it in the craft zone, at the drumming sessions and in the queue for food at No Bones Jones.

“We’ve come to be inspired,” says Robin Dale-Thomas, who came from Pembrokeshire with his girlfriend Yoshie and their children Tatsuki, 6, and Laluna, 4. The Dale-Thomases get power from solar panels at home — like most people here, they are greener than average — but they don’t want to be complacent.

The same goes for Tim and Emmanuelle Kirby from Bristol, who brought their children Stephanie, 4, and Benoit, 2. They use an ethical bank, buy second-hand furniture and clothes and do not have a car.

What do they all think of Cameron and Goldsmith and their attempt to turn the Tories green? “David Cameron cycles to work with a car following behind him,” says Andy Hope, who travels around with his Green Roadshow. But he concedes that he may owe the increased interest in his roadshow to the Tories and other unexpected allies. “Climate change has entered the mainstream,” he says. “And I suppose that is partly down to people like Cameron.”