The Communist Party of Great Britain (CPGB) was the largest communist organisation in Britain and was founded in 1920 through a merger of several smaller Marxist groups. Many miners joined the CPGB in the 1926 general strike. In 1930, the CPGB founded the Daily Worker. In 1936, members of the party were present at the Battle of Cable Street, helping organise resistance against the British Union of Fascists. In the Spanish Civil War, the CPGB worked with the USSR to create the British Battalion of the International Brigades, which party activist Bill Alexander commanded.

Marxism is a political philosophy and method of socioeconomic analysis. It uses a materialist interpretation of historical development, better known as "historical materialism," to understand class relations and social conflict. It also uses a dialectical perspective to view social transformation. Marxism originates from the works of 19th-century German philosophers Karl Marx and Friedrich Engels. Marxism has developed over time into various branches and schools of thought, As a result, there is no single, definitive Marxist theory. Marxism has had a profound impact in shaping the modern world, with various left-wing and far-left political movements taking inspiration from it in varying local contexts.