Triads in the United Kingdom
Triads in the United Kingdom first appeared during the post-World War era with the 14K Triad emerging in Chinese communities in London, Birmingham, Liverpool and Manchester in England and Glasgow, Edinburgh and Dundee in Scotland as early as 1952. A later migration followed as members of Chung Mon's organisation fled Amsterdam following the Triad leader's death in 1975 as well as those from Hong Kong during the 1980s.
Source: Wikipedia — Triads in the United Kingdom (CC BY-SA 4.0)