The history of communism is inextricably linked with Britain. This work charts the history of Marxism and Communism in Britain, through the activities of the Social Democratic Federation and the Communist Party of Great Britain, chronicling everything from their relations with the trade unions and the working classes to the struggle against fascism. In so doing it presents a challenging picture of a revolutionary force within Britain guided after the First World War by Soviet Russia and committed to the ideal of international communism. The Comintern (Communist International), founded in Russia after the Bolshevik Revolution, sought to provoke communist revolutions worldwide until its dissolution in 1943. The authors reveal that despite protestations to the contrary the British Communist Party and its leadership were dominated by the Comintern. For as long as the Soviet Communist Party offered clear guidance through the Comintern, British communists followed its line faithfully. It was the failure of Moscow to provide these clear policy guidelines that, the authors argue, led to the collapse, and near-extinction, of communism in Britain.