This article discusses the potential for constitutional impact of Brexit on the United Kingdom’s constitution. Some argue that Brexit entails the restoration of effective parliamentary sovereignty and, thereby, a reaffirmation of the UK’s traditional constitution. However, Brexit increases pressure on unstable points in the traditional constitution, making other outcomes possible. One possibility is the emergence of a ‘populist’ democracy which, while retaining the legal framework of the traditional constitution, gives the UK executive greater power relative to the UK parliament, judiciary and devolved governments. The institution of referendum might also have a distinctive place within this new populist democracy, though the constitutional status of the referendum remains very unclear. In this scenario, UK developments have something in common with shifts towards ‘post-liberal’ and ‘populist’ polities in other nations. Alternatively, the pressures increased by Brexit might yet push the UK – or post-UK – further in the direction of democratic constitutionalism, ultimately making it a more ‘normal’ – ironically, perhaps a more ‘European’ – democratic state.