For much of the twentieth century, relations between Britain and the Soviet Union were defined by mutual hostility and distrust. From the aftermath of the Bolshevik Revolution until the last days of the Cold War, the British establishment was greatly concerned about the threat of Soviet-inspired subversion and secretly monitored thousands of citizens because of their real or perceived links to communism, the Soviet Union, or both. Enemy of the State reveals the story of how Britain's intelligence services watched individuals on the grounds of protecting democracy. Using phone taps, hidden microphones, mail interception and covert break-ins, this covert surveillance led them to investigate, amongst others, trade unionists, scientists, politicians, anti-nuclear protesters, and those campaigning against apartheid. The culture of secrecy permeating British institutions has meant that the extent of the activities of British security and intelligence establishments has often been unknown. Drawing on files of the British government and intelligence agencies, Oliver Price argues that whilst communism had little impact on British politics, the fear of it led to the widespread monitoring of political and protest groups in Britain. Britain was long considered a country in which so-called 'political policing' and the surveillance of civilians was resisted. As Enemy of the State shows, the events of the twentieth century reshaped official attitudes and normalised widespread surveillance.