The United Kingdom faces with two major federal constitutional debates. The first is about the nations which comprise the British state and hence the division of power between Westminster and regional parliaments of Wales, Scotland and Northern Ireland. The second surrounds the United Kingdom and the European Union. This text explores the British engagement with the federal idea from the early 1600s onwards, and sets contemporary discussions in context. In the past four centuries, the British have often looked to the federal idea as a possible solution to problems of the unity of the United Kingdom and of the British Empire. This period has also seen successful adoption of federalism by many countries, including Britain's former colonial possessions. John Kendle examines the break-up of the first British empire and the development of modern federalism. As well as discussing the Anglo-Irish relationship and the United Kingdom's relationship to Europe, the author focuses on other contemporary issues such as the world order, imperial federation and decolonization.