The previous Chinatown in the Limehouse region of London was known more for its opium dens (which were legal) and slum housing which are normally associated with immigrants in a town or city, not the Chinese restaurants and supermarkets in the current Chinatown. A number of elderly Chinese still live in this area.
Japanese, Singaporeans, and Koreans, as well as Chinese live in today's Chinatown.
For more information on why Chinatowns developed see Chinatown.