Organic food is no longer just for the affluent, with half those in lower socio-economic groups now buying it, according to Peter Melchett, policy director of the Soil Association,

Delivering the City Food Lecture, Melchett said shoppers increasingly interested in quality and taste had found organic affordable.

"This is no longer simply a middle-class market. Over 50% of people in lower-income groups are buying organic food and if they buy direct from farmers, or via box schemes, it needn't be more expensive than non-organic in supermarkets.

"Studies have shown that if shoppers shift away from ready meals and diets high in meat, and buy more healthy, fresh, seasonal produce, and less but better-quality meat, the additional costs are offset."

Major retailers were playing a role in increasing uptake, he said, citing the fact that organic food was a star performer in a record Christmas for Tesco, and that its organic sales had grown 39% in 2006.

"People will make greener choices if they get the right information, opportunity and incentive," he said.

The UK was on the cusp of a revolution in food and farming practices thanks to growing consumer concerns with health and the environment, he added. "It's self-evident that a farming system that's better for our environment is better for our overall health."