As celebrity crazes go, this latest one is reasonably harmless: not hard-core drinking, drug-taking or even excessive slimming. No, the current fad for celebs who make a living out of appearing on the covers of Heat magazine is nothing other than knobbly vegetables. And free-range pigs. Fried up, that is, with some organic onion rings.

“Green” food, grown without pesticides or hormones, is so hot at the moment that no right-minded member of Soho House would dare to throw a dinner party without a slab of organic fare on the menu.

It seems as though the rest of us have also been smitten by greenery. Slowly but surely it has become de rigueur to recycle stuff, rather than just chuck it away. The government has set statutory targets for the recycling and recovery of household waste; across the nation, two-tone bin systems outside residential homes with paper, bottles and boxes in one bin and veg peelings in another are typical rather than unusual. Manchester city council has an entire section on its website devoted to recycling everything — from beds to baby wipes.

Meanwhile, on the high street things have gone much further than the Planet Organic label. Marks & Spencer has had a huge success with its ethical marketing drive which encourages shoppers to “look behind the label” and focus on the source of its products.

Trumpeting non-battery eggs in its ready-to-eat meals and promoting the use of Fairtrade cotton has probably done more for the market recovery of M&S than anything, including those advertising shots of Twiggy. “The evidence collected by the company indicates this was the most positive campaign the business has ever run,” a report by Citigroup analysts said last week.

Being green is now accepted as being rather chic; a straightforwardly good idea worth signing up to, rather than something outwardly virtuous which requires a keen commitment to body hair and a vegan diet. Of course there are people who take things to extremes, such as the environmentally conscious bridesmaid Barbara Haddrill, whose concern about carbon dioxide emissions is such that she is travelling overland to the wedding of her best friend, rather than by aeroplane. That the wedding is in Brisbane and Barbara is in Wales only adds, in Barbara’s view, to the excitement of the big day.

But for every person like Barbara (whose journey, if taken by air, would produce 5.2 tons of carbon dioxide, or the equivalent of heating five houses for a year), there are hundreds of others who now feel it is just not acceptable to jet off to Barcelona for a hen weekend, or fly to Paris when Eurostar is so much kinder to the environment. Indeed, a Channel 4 conference on global warming had to cope with some of the participants appearing by video phone because of their reluctance to travel by air in order to take part.

Yet probably the single most crucial factor in helping to encourage this cultural sea-change is the celebrity take-up of green zeal. Liz Hurley, whose adoration of an organically reared (and very hairy) Gloucester Old Spot ended up in most of the papers last week, is said to be converting her 400-acre Cotswolds farm to organic production and launching a brand of organic baby foods (whether the labels will be designed by Donatella Versace is, as yet, unknown).

Arnold Schwarzenegger has already outlawed gavage, the force-feeding of geese to produce foie gras, in California and is pushing for cuts in CO2 emissions in the state. Sergey Brin, co-founder of Google (and worth £6.8 billion), uses a solar-powered mobile phone while wealthy British socialites from Zac Goldsmith, son of James Goldsmith and editor of The Ecologist, to Robin Birley, owner of Annabel’s nightclub and a campaigner against global warming, are also doing their bit to turn green into the new black.

Understandably, the open-toed sandal brigade is rather chuffed about being taken up by the Jimmy Choo bunch. Tony Juniper, director of Friends of the Earth, describes the embrace of people such as Gwyneth Paltrow as a “high water mark” for the green moment. It would seem that he has been waiting for years for the clarion call from La Hurley and her pigs.

“To solve the huge environmental problems the world faces now, we need political change but we also need cultural change,” he tells me. “People need to see that things can change. And if it’s going to be made more fashionable thanks to interest from some high-profile people, that’s fine.”

However, Juniper speaks to me from Stansted airport having just arrived off a plane from Amsterdam. What? “I’ve attended a meeting of FOE International,” he confesses. “And there was no alternative to flying. Like everyone else in the country, I face harsh realities.” All right, then.

Meanwhile, the Soil Association is gearing up for its Organic Fortnight next month. It has hired Donna Air, the actress and model, to be the “face” of the event. Why? “She is a young, fresh face who has a genuine passion and enthusiasm for organic food,” says Robin Maynard, the organisation’s campaign director. “She is a young mother herself and is not only interested in the taste but also the health benefits of organic food.”