Abstract: 1820 was a year of European revolutions. The events of these twelve months were probably the greatest test any British peacetime government confronted during the nineteenth-century. However, historical understanding of this pivotal year has long been fractured by over-emphasis on the constitutional crisis caused by the attempt of King George IV to divorce his Queen (Caroline). The continuing problems of post-war economic and social dislocation are less clearly understood. The attempted mass assassination of the British Cabinet (‘Cato Street’) is typically dismissed as the work of isolated psychopaths, when it was an ill-judged consequence of a much wider conspiracy. Other episodes are largely neglected, for example the general election caused by the death of George III, uprisings in northern England and Scotland, and the dramatic acceleration of violent unrest (“Ribbonism”) in western Ireland. The Government was constantly alert to the possibility of concerted links between British and Irish – and even French – unrest.