The introduction makes a case for addressing the ‘break-up of Britain’ as a problem of global history. For decades, historians of remarkably diverse leanings have thrown their intellectual weight behind a presumed connection between the historical burden of imperial decline and the slow depletion of shared British sentiment since the Second World War. Yet invariably, the end of empire tends to be framed as an abstract tipping point, with little sense of its real-life interactions or everyday consequences - as though its mere dissolution were causation itself. But if social identities are inherently relational, arising out of intricate patterns of material and cultural exchange connecting peoples across wide distances, then focusing solely on the ‘British of Britain’ can provide only a partial and incomplete perspective. By incorporating the fate of Britishness in the many corners of the world where it has long since ceased to command any popular allegiance, the diminishing strength of unitary sentiment in the contemporary United Kingdom emerges in a whole new light. The argument, structure and empirical range of Untied Kingdom all proceed from this fundamental premise.