This book examines entryism in the context of the revolutionary socialist left in Britain, from the inception of the Communist Party of Great Britain in 1920 to the departure of Militant from the Labour Party in 1992.

Nicolas Sigoillot holds a PhD in English Studies and teaches at the Institut d'Etudes Politiques in Lyon. His dissertation focused on Entryism within the Labour Party. His research focuses on socialism in Britain, political strategy, and videogame representations of historical concepts related to socialism.

Part 1: Theoretical Considerations 1 Social Democracy, Leninism, and Trotskyism 2 A Critical Examination of the Previous Definitions of Entryism Part 2: The CPGB Before the Second World War 3 The CPGB at its Early Days and the Affiliation Tactic 4 The CPGB in the 1930s: Entryism at the Service of the Popular Front Part 3: The Early Days of British Trotskyism 5 The Splits Over Entryism in the Early British Trotskyist Movement 6 Flexibilities and Sectarianisms: Coherences and Contradictions Within the WIL And RSL 7 From the Foundation of the RCP to the Split Over the Question of Entryism: A Never-Ending Circle? Part 4: British Trotskyism After the War: Different Traditions, Different Entryisms 8 From Secrecy to Sectarianism, the Healyite Tradition in Action 9 The Peripheralists: The Cliffites and the IMG Tradition 10 Militant, and the Backlash Against the Successes of Long-Term Entryism