This book examines how the Crown has performed as Head of State across the UK and post war Commonwealth during times of political crisis. It explores the little-known relationships, powers and imperial legacies regarding modern heads of state in parliamentary regimes where so many decisions occur without parliamentary or public scrutiny. This original study highlights how the Queen's position has been replicated across continents with surprising results. It also shows the topicality and contemporary relevance of this historical research to interpret and understand crises of governance and the enduring legacy of monarchy and colonialism to modern politics. This collection uniquely brings together a diverse set of states including specific chapters on England, Scotland, Northern Ireland, Sri Lanka, Malaysia, Brunei, Ghana, Nigeria, Zimbabwe/Rhodesia, Australia, Tuvalu, and the Commonwealth Caribbean. Viceregalism is written and conceptualised to remind that the Crown is not just a ceremonial part of the constitution, but a crucial political and international actor of real importance.