Free-range chickens are flying off the shelves after a recent TV exposé of factory farming, according to London Farmers' Markets.

Farmers have reported a 20 per cent increase in demand at some markets since Jamie Oliver and Hugh Fearnley-Whittingstall's campaign for better treatment of birds.

"It's a great start to the year," said Tim Norris of Harvest Moon, an organic poultry farmer from Hertfordshire.

"It has restored my faith in the British public and made me want to continue farming."

Mr Norris's organic poultry is available at Wimbledon Farmers' Market every Sunday from 9am to 1pm, at Wimbledon Park Primary School, Havana Road.