This authoritative history of the Treasury provides a new perspective on public policy-making in the twentieth century. It explores the role and functions of the Chancellor of the Exchequer and the consequent implications for the changing role of the Treasury. As the key department in British government, the Treasury developed growing responsibility for managing the national economy and became increasingly involved in international relations from the time of the First World War. The author examines the relations between ministers and their official advisers, and the growing influence of economists in Whitehall.