In the aftermath of the First World War British politics were subordinated to the goal of reconstructing a multilateral trade and payments system. This decision must be understood as the result of the peculiar structure of British capitalism wherein mercantile and financial activity rather than manufacturing industry provided the core of wealth of the dominant community. For a decade, Britain made a signal contribution to the restoration of multilateralism. With the world at a turning-point in 1928, British policy remained committed to reform through multilateral action, particularly once the Labour party resumed office. But the practical effect of policy was the opposite of that intended. Dogmatic opposition to all second-best alternatives helped drive all countries, Britain included, away from internationalism towards a narrow nationalism and economic protectionism. The account ends in 1932 when Britain embarked upon an active imperial policy while the rest of the world headed towards another war. Using a wide range of primary sources, the author presents an account which integrates the economic, political and diplomatic events of the period.