There's quite a few here: http://www.tritoncycles.co.uk/products.php?plid=m5b0s208p0
@hippy 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.
There's quite a few here: http://www.tritoncycles.co.uk/products.php?plid=m5b0s208p0