Back in the distant recesses of time, when we all believed the earth was flat and Turkey Twizzlers were just a bit of harmless fun, 'eco-friendly fashion' was a virtual oxymoron. Living a green lifestyle was something earnest people did to make the rest of us feel bad. Ethical trendiness consisted of wearing hand-knitted Peruvian beanie hats, protesting against the Newbury bypass and owning at least one CD of a rainforest tribe performing breathy pan-pipe tunes.

But that was before Anya Hindmarch. That was before she designed the 'I'm not a plastic bag' cloth shopping tote. When the £5 bag went on sale at Sainsbury's last April, all 20,000 of them sold out in an hour. Within days, they were exchanging hands on eBay for £200.

'It spread like wildfire,' says Hindmarch, 39, sitting at a long, white marble table in the Daylesford Organic café in Chelsea. 'Eighty thousand people queued on one day in England to buy that bag.'

The £5 tote rapidly became an iconic style item. Being ethical had never seemed so cool. 'I'm not decrying the plastic bag but we need to start thinking about how we use them,' Hindmarch says. 'I have five children and I used to pick up 35 plastic bags at the supermarket, then throw them away instead of re-using them.'

The bag was made in China, by workers typically paid 20p an hour - a revelation that caused much huffing and puffing in the press - but Hindmarch insists that double the minimum wage was paid and that the products were shipped by sea. She spent several months looking at the supply line, at how small but crucial improvements could be introduced gradually over a period of time - but she readily acknowledges that it is not yet perfect. 'Fashion is criticised for being frivolous but something like that shows the power of fashion to influence people,' she says. 'For me, it was about raising awareness, not about selling lots. The bag cost more to make than we sold it for.'

Soon, celebrities were flocking to demonstrate their eco-credibility. You could barely put out your recycling bags without bumping into Natalie Portman skipping up the aisle at Whole Foods with her self-made vegan shoes and beatific smile. The fashion pack started zipping around town in Toyota Priuses, talking about carbon-offsetting and buying African village goats for Christmas.

If the bag made people think about how they took their shopping home, it also made them ponder where their supermarket food came from. Celebrity chefs got in on the act - Hugh Fearnley-Whittingstall with his battery hens and Gordon Ramsay turning his garden into a pen for his Berkshire sows (Trinny and Susannah). Now George Bush's niece, Lauren, has designed her own eco-bag (the 'Feed Bag' costs $34) made from burlap, with proceeds going to the UN's World Food Programme.

'Living more ethically has definitely become more fashionable,' says Hindmarch. 'My children are certainly more aware than I was and much better educated about nutrition. 'We don't find the idea of battery chickens comfortable any more. That's why I'll always try to buy organically.'

Fortuitously, Hindmarch lives round the corner from Daylesford Organic, the impeccably posh café and food emporium founded by Lady Bamford, wife of JCB tycoon Sir Anthony Bamford. Inside, the decor is all lime-washed white benches and willow-branch stair rails. The shelves are lined with vast truckles of cheddar cheese, sourced from the Bamfords' Staffordshire estate. A table by the door offers you a chance to buy that perennial kitchen-cupboard stalwart - Romanian bee pollen. Everything is organic and sustainable and quite possibly has the capacity to make you a purer person simply by looking at it. 'I love coming here,' says Hindmarch. 'I think I've been slightly brainwashed by Daylesford.'

It is rather hard not to be won over by the meticulous attention to detail and the polite staff, liveried in brown aprons and starched white kitchen uniforms. Wordlessly, they deliver us mouth-watering trays of organic smoked salmon, bowls of Bircher muesli and boiled eggs with soldiers, piled high like a Jenga puzzle. Then, just as we are leaving, they present us each with a vine-tomato-scented candle. In a paper bag, naturally.