This chapter traces Ireland as a foundational zone of influence and creative disruption in the British imagination. Ireland’s political status has been altered by the Anglo-Irish relationship across centuries, while Britain, in turn, has been shaped by its interaction with the otherness of its closest island neighbour. Twelfth-century texts demonstrate that Ireland has acted as a foil to Britain’s imperial imagination, and it continued to do so throughout the subsequent literary and political history. The chapter discusses depictions of Ireland from Gerald of Wales to Edmund Spenser to William Shakespeare. Then it turns to examine the influence of Irish literature on the British imaginary. The enduring influence of Maria Edgeworth, W. B. Yeats, James Joyce, Elizabeth Bowen, Samuel Beckett, and Seamus Heaney allows Britain to see itself through Irish eyes. Often, they reveal the occlusions and silences that exist within Britain’s self-imaginings. With Brexit shadowing the contemporary relationship between Britain, Ireland, and, of course, Europe, this dialogical Anglo-Irish relationship, whereby Ireland both reflects and distorts Britain’s image, becomes all the more significant.