Chief Economic Adviser to the Treasury, Ed Balls, sets out the government’s approach to making the decision about British membership of a single European currency in an historical context. The basis for deciding whether there is a clear and unambiguous economic case to join the single currency is the Treasury’s detailed assessment of the ‘five economic tests’. The tests are designed to avoid past failures of politicians and policymakers who paid insufficient attention to the economics in making key decisions affecting the national interest. Balls reflects upon historical examples of such failures and lessons to be learned, with a particular historical focus on 1925 and the decision to re-enter the Gold Standard.