An old chestnut recycled: Miss Earth

George Sargent looks bemused. He's sitting with a pint in a hotel bar in Coventry, with one eye on the Ashes and the other on Miss East Kilbride who has just come in wearing a remarkable above-the-knee, strapless dress made entirely from the pages of a Glasgow telephone directory.

It took her 50 hours, and the help of a very supportive boyfriend, to pleat hundreds of individual pages to form the skirt and then make the fitted bodice. Time well spent, she believes, if it helps her to win the "eco-dress" section of the Miss Earth beauty pageant.

Three miles outside Coventry town centre, the Chace Hotel is playing host to 62 girls, aged 18 to 25, hoping to be crowned this year's Miss Earth for England, Scotland, Wales and Northern Ireland, and book a place at next year's global final in the Philippines. As my taxi pulls in to the hotel car park, I suddenly find myself surrounded by a rush of young beauties dressed in green (get it?), heading out for the first photo session of the weekend.

The eco-girl concept seems to have struck a chord among marketers as part of the wider global phenomenon that is Eco Inc.

It also meets with unequivocal approval from Mr Sargent, 66, a retired businessman and local magistrate: "I come in here every night to meet my ladyfriend for a drink, so I wasn't expecting this. The girls look amazing, I can't believe some of these dresses, and I've seen a few things in this bar over the last 40 years," he says, distracted suddenly by Miss Croydon, a rugby player, who is wearing a dress made out of empty beer cans and bin bags.

Notwithstanding the incongruity of young women parading their looks in the name of saving the planet, the Miss Earth contest is catching on. In 2003, it adopted the catchy slogan "Beauties for a cause" and created the Miss Earth Foundation to promote environmentally friendly projects such as planting trees, picking up litter and pushing eco-brands.

Now in its ninth year, the contest has established itself as the world's third biggest beauty contest after Miss World and Miss Universe. And others are climbing on the environmental bandwagon: America's Top Green Model can be expected on our TV screens later this year.

The competitors profess themselves unfazed by what many would see as the contest's inherent contradictions. "It's not all about how you look, it's about what you do for charity and the environment as well," says Miss Oxfordshire, shivering in a slight green "vintage" party frock bought from eBay. Natasha Medlin, 22, is living her childhood dream of dressing up in beautiful clothes while strutting her stuff on stage. She wants to get into promotional work for cars and motorbikes. Hopefully, she has a passion for the G-Wiz or the Toyota Prius, otherwise her green credentials will start to look suspect.

Geerati Thatsa, 18, is the very shy Miss Southsea. Wearing her mum's dress, which she describes as "vintage, from the Nineties", she admits her mum pushed her into entering. She recycles, reuses plastic bags and donates her clothes to charity shops, but thinks most girls are here for the beauty contest rather than the green one. No one I talk to disagrees, not even the organiser, Louise Brown-Powell, herself a former beauty queen.

"What's wrong with trying to spread an important message using beauty competitions?" she asks. "I bet more people take notice of us than a newspaper story. I would be happy for my daughters to get involved when they get older; it's all about having fun."

For most competitions, including Miss Earth, girls must be single, have never given birth, be in excellent physical condition, and, crucially, be able to raise £200 in sponsorship to enter, though some have dropped their price in a nod to the recession.

In one corner of this slightly dated hotel bar, a small group of the girls tell me how terrible life will be when they're too old for the beauty pageant circuit. They enter all the competitions they can: Miss England, Miss Intercontinental, Miss Black Beauty – sending up to 500 emails a year to secure sponsorship deals.

Jennifer Charles, 24, is Miss Leicester. She plans to hang up her sash next year, after eight years on the circuit. "I watched Miss World from when I was young, and think of a beauty queen as the perfect woman. To be on stage and have everyone admire you, well, who wouldn't love that? It's addictive. I went through a lot when I was growing up, but beauty pageants helped me become a more mature woman; it's like going to finishing school."

As beauty pageants go, Miss Earth has things going for it. The contestants are a diverse and likeable bunch. There are no bitchy comments or reports of sabotage. Some of them are drop-dead gorgeous – a few of them have clearly spent too much time watching Dynasty and hanging out with Mr Fake Tan – but lots are, while not plain, not beautiful either. There are black and Asian girls, and some are even eating chips, washed down with Coke (diet, of course). And everyone I speak to says pageants have helped their confidence.

But as an exercise in environmental awareness, Miss Earth looks opportunistic at best. The contestants are getting ready to show the judges their eco-scrapbooks, but as they prepare for the interviews there is no talk of carbon emissions and food security, and much chatter about spray tans and false eyelashes. These girls are not going to save the planet. Nor are they likely to become supermodels. But they're giving both their best shot.