Here a list (think they have all probably been mentioned already)
http://www.pubnetwork.com/london/Breweries%20in%20London.htm
@kidboy started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
Here a list (think they have all probably been mentioned already)
http://www.pubnetwork.com/london/Breweries%20in%20London.htm