More than 500 restaurants have signed up within the first month of the RSPCA’s latest campaign, committing themselves to cage-free eggs.

The restaurants include all National Trust restaurants and tea-rooms, Sainsbury’s in-store restaurants, Hugh Fearnley-Whittingstall’s River Cottage canteens and restaurant chains Giraffe and Leon.

Launched last month by TV chef and restaurateur Antony Worrall Thompson and a host of MPs, the Freedom Food’s “Simply Ask” campaign aims to aimed at encouraging consumers to consider what eggs are used in their food when eating out.

Freedom Food marketing manager Caroline Gauntlett said: “Simply Ask has got off to a really positive start. With more than 500 restaurants, cafes and pubs already signed up and calls from potential new members daily, it has far exceeded our expectations.

“It is clear from the initial results we have found a campaign with which both restaurants and their customers can engage. It is proving to be a real recipe for success.”

However she is keen to stress that there is still a long way to go with the majority of restaurants still using cage eggs.

“Simply Ask” isn’t a quick-fix solution. We recognise that many restaurants can’t switch to using cage-free eggs over night. But we want those restaurants to start putting plans in place now to make the change to cage-free eggs by the end of 2010.”