The Communist Party of Great Britain (CPGB) was the largest communist party in Great Britain, although it never became a mass party like those in France and Italy. It existed from 1920 to 1991.
The Communist Party of Great Britain was founded in 1920 after the Third International decided that greater attempts should be made to establish communist parties across the world. The CPGB was formed by the merger of several smaller Marxist parties, including the British Socialist Party, the Communist Unity Group of the Socialist Labour Party and the South Wales Socialist Society. The party also gained the support of the Guild Communists faction of the National Guilds League, assorted shop stewards' and workers' committees, socialist clubs and individuals and many former members of the Hands Off Russia campaign. Several branches and many individual members of the Independent Labour Party also affiliated. As a member of the British Socialist Party, the Member of Parliament Cecil L'Estrange Malone joined the CPGB.