What Recent developments in UK politics have reignited debates about Scottish and Welsh separatism, and the enduring tensions over the Northern Ireland border, as the polarised politics of Brexit have left a legacy of speculation about an impending ‘Break-Up of Britain’. This project examines the deeper historical antecedents, taking in the wider perspective of the end of the British Empire. To what extent can the eclipse of unifying British symbols and sentiments be understood in terms of a failure of British identities to resonate globally since the Second World War? The question invites a global approach, taking in perspectives from Australia, Canada, Gibraltar, Hong Kong, India, Kenya, New Zealand, South Africa and Zimbabwe (and the ‘four nations’ of the United Kingdom itself). Why For more than fifty years, historians and social scientists have identified possible links between the contraction of Britain’s empire and the fragile unity of the UK, with scholars of diverse leanings lending support to the idea: from J. G. A Pocock to Tom Nairn, Raphael Samuel, Linda Colley, Krishan Kumar, Norman Davies, and David Marquand. Yet remarkably, the link between imperial collapse abroad and post-imperial corrosion ‘at home’ has never been developed beyond a crude proposition, and remains remarkably under-researched. This book offers the first comprehensive analysis based on extensive empirical research, with a view to reconceptualizing the problem by integrating metropolitan and imperial perspectives. How The book is both a synthesis of a large and unwieldy subject as well as a novel empirical study in its own right, forging linkages between multiple crises of British selfhood at empire’s end. Rather than account for every manifestation in every corner of the globe, distinct choices have been made in terms of chronological, geographical and thematic emphasis, structured around the key registers of transcontinental British community that buckled under the pressures of post-war decolonization. The empirical material has been selected accordingly, taking in archive and manuscript collections in more than ten countries. The book’s thirteen chapters cumulatively build an argument based on connections and comparisons drawn between changing community sentiments in multiple hemispheres. SSR This is a project where the immediate social and political repercussions are yet to be fully played out. The ‘Break-Up of Britain’ remains a polemical as much as a scholarly proposition, and much prior research has inevitably been dominated by partisan perspectives. The wider remit of this project draws the focus away from unresolved present-day disputes to consider instead the historical conditions that produced these divisions to begin with. Examining the problem in other parts of the world where Britishness now exists only in the past tense also offers an invaluable (and arguably sobering) perspective that is usually absent from separatist political debates in the UK. There is thus unique potential here to inform these debates, without necessarily making a direct political intervention.