Sir Paul is urging Britons to cut out eating all flesh on Mondays, in a concerted effort to cut down on C02 emissions. The initiative is based on a similar scheme that has run successfully in Australia, where families adopt a vegetarian only diet one day a week by forcing a cut back in the process of meat production, thus allaying the onset of global warming.

The singer, who had some successs writing songs with his pal John Lennon back in the 60’s, told The Grocer trade magazine, that if people were unable to cut out animal consumption perminently, then they could at least take easy steps to help in the fight against climate change.

“A lot of people go to the gym on a Monday. With meat-free Mondays, it’s a bit like going to the gym but with the added advantage of protecting the planet,” said Sir Paul, before adding: “One of the most significant conclusions of the recent report on climate change was that we should eat less meat. This is not the Vegetarian Society that said that. It’s the UN.”

Science does appear to back up his claim. According to earthsave.org, “by far the most important non-CO2 greenhouse gas is methane, and the number one source of methane worldwide is animal agriculture.

“Animal agriculture produces more than 100 million tons of methane a year. And this source is on the rise: global meat consumption has increased fivefold in the past fifty years, and shows little sign of abating. About 85% of this methane is produced in the digestive processes of livestock, and while a single cow releases a relatively small amount of methane, the collective effect on the environment of the hundreds of millions of livestock animals worldwide is enormous.”

Vegetarianism is even being hailed as the new Prius, because of it’s benefits to the environment. The ex-Beatle and Wings man owns a Lexus LS600H, given with gratitude for promotional work the popstar recently did, though he was reportedly fuming when the car was flown to him from Japan, doing considerable damage to his personal carbon footprint.

It’s not just the old guard getting in the act; McCartney is the latest celebrity to appear in a Peta advertising campaign donning an ‘eat no anima’l t-shirt, alongside the likes of Alicia Silverstone, Casey Affleck and Forest Whitaker. Fledgling susperstars such as Leona Lewis are getting in on the act too. The singer, a hit on both sides of the Atlantic, recently said: “I am vegetarian so I don’t have clothes, shoes or bags made from leather or suede or any animal products… I’m on a mission”.

The Hackney born singer, nominated for the forthcoming annual Peta Sexiest Vegetarian awards 2008, doesn’t generally do things by halves, so don’t say you’ve not been warned.