In recent years, there has been substantial academic re-appraisal of Enoch Powell alongside a growing public realisation, increased by the debate over Brexit, that his interests were wider than immigration and notably included opposition to British membership of the European Community – a topic that this article probes further. It begins by examining Powell’s understanding of the British nation as a unitary state, centred on Parliament, that underpinned his interpretation of both Conservatism and Unionism. Then, covering the period up to the 1975 referendum, the article analyses exactly how Powell argued that membership of the European Community threatened parliamentary sovereignty. It situates Powell’s thinking in the context of arguments made by others and explores the connections made by Powell between the threat from Europe and the history of Parliament itself, particularly the formation of the unions with Scotland and Ireland. The article shows that while Powell’s arguments were marginalised in the later 1970s and for much of the 1980s, they were revived from the early 1990s – albeit it in a changed constitutional context.