Islington Farmers' Market
Islington Farmers' Market was the first Farmers' Market to open in London, it opened in 1999. The market was set up by food writer Nina Planck, who established the organisation London Farmers' Markets. The market is still running, having changed location twice. It is currently held on the Western end of the historic market street, Chapel Market.

Islington Farmers' Market was the first Farmers' Market to open in London, it opened in 1999. The market was set up by food writer Nina Planck, who established the organisation London Farmers' Markets. The market is still running, having changed location twice. It is currently held on the Western end of the historic market street, Chapel Market.
Check the official site before travelling; hours and prices can change.
More markets

Borough Market
London's defining food market — go early Saturday, eat your way around the perimeter.

Columbia Road Flower Market
Sunday-only flower market in the East End — 8 a.m. for choice, 2 p.m. for prices.

Maltby Street Market
Borough's smaller, scruffier sibling — railway arches, weekend only.
Source: wiki-list