The name Chinatown has been used at different times to describe different places in London. The present Chinatown is part of the Soho area of the City of Westminster, occupying the area in and around Gerrard Street. It contains a number of Chinese restaurants, bakeries, supermarkets, souvenir shops, and other Chinese-run businesses.
The present Chinatown, which is off Shaftesbury Avenue did not start to be established until the 1970s. Up until then, it was a regular Soho area, run-down, with Gerrard Street the main thoroughfare. It was dominated by the Post Office, facing Macclesfield Street, and other major establishments were The Tailor & Cutter House, at 43/44, now a Chinese supermarket and restaurant, the Boulougne Restaurant, near the Wardour Street end, and by Peter Mario's Restaurant at the other end. Other businesses included a master baker's, the Sari Centre, Lesgrain French Coffee House, Harrison Marks' Glamour Studio, an Indian restaurant and various brothels. Probably the first Chinese restaurants opened in Lisle Street, parallel to Gerrard St, and then spread gradually. The Tailor & Cutter did not close down until around 1974.
The area boasts over 80 restaurants showcasing some of London's finest and most authentic Asian cuisine.
The nearest London Underground stations are Leicester Square and Piccadilly Circus.

Source:
http://en.wikipedia.org/wiki/Chinatown,_London

Google Maps:
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