Cannabis has never been a more controversial substance in Britain. Over the last decade it has been reclassified twice, has been the subject of a range of official investigations and scientific studies, and has provoked media campaigns and all manner of political gesturing. This book seeks to understand this period by placing it back into the historical context of the long-term story of cannabis and the British. It takes up where its predecessor, Cannabis Britannica: Empire, Trade and Prohibition, 1800–1928 left off. It traces the story back into the last days of the Empire, when Britain controlled cannabis-consuming societies in Asia and Africa even while there was little taste for the drug back home. It shows that cannabis was caught up in control regimes established to deal with opium and cocaine consumption, while it fell out of favour as a medicine. As such, when migration after the Second World War brought the Empire's cannabis consumers to the UK, they faced hostile attitudes towards their favourite intoxicant. From that time on a growing number of groups and agencies took an interest in cannabis. Ambitious bureaucrats in the Home Office saw in it an opportunity to draw resources into the Drugs Branch, while the police began to use laws related to it for a number of other purposes. Experts ranging from pharmacologists to sociologists formed committees on the subject and its association with colonial migrants lent it an exotic aura to the politically minded of the 1960s counter-culture and the working-class youth of Britain's inner cities. Since the 1970s governments were content to devolve responsibility to the police for working out the best legal approach to the substance, and efforts to wrest this back from them proved difficult a decade ago. The volume considers all of these trends, details the often eccentric characters that have shaped them, and concludes that current positions and arguments on cannabis can only be properly assessed if their historical origins are clearly understood.