This opening chapter mounts an argument about the overseas projections of imperial identity, surveying the material and ideological conditions for imagining Britishness on a global scale. It considers how imperial expansion from the early seventeenth century created the need to make sense of highly fluid movements of people in radically new social formations. The language of Britishness could be employed across enormous distances, but the resultant heterogeneity also engendered fault lines that would pose formidable problems in the years ahead. The veneration of British constitional freedoms rested uneasily with practice of ruling ‘inferior races’ by flagrantly authoritarian means - furnishing the definitive paradox of a nominally liberal British world. Contemporaries went to great lengths to contain the anomalies, employing a highly elastic conception of ‘Great Britain’ that eluded conventional categories of inclusion and exclusion. To be British was to inhabit a moving frontier comprising a patchwork of peoples who never seriously demanded or developed an integrated, transoceanic popular sovereignty. As such, the idea of Britain — more so than England — became heavily freighted with the imagined properties of global reach, and hence more vulnerable to the perils of imperial decline.