The period from the twelfth century to the Wars of the Roses witnessed a dominant tradition of secular prophecy engaged with high political affairs, which this book charts, discussing the production of prophetic texts forecasting the rule of the whole of Britain by the kings of England. The author draws on the prophetic works of familiar authors and names, such as Geoffrey of Monmouth and Thomas of Erceldoune, alongside previously unpublished manuscript material, to study identity formation among medieval political elites. Alongside English prophetic texts, she explores competing visions of the British future produced in Wales and Scotland, with which English prophetic authors entered into an overt dialogue; this was a cross-border exchange which in many ways shaped the development of this deeply influential discourse. Prophecy is revealed to be a dynamic arena for literary exchange, where alternativeimaginings of the future sovereignty of Britain vied for acceptance, and compelled decisionmaking at the highest political levels.