Barry Eichengreen, professor of economics at the University of California, Berkeley, is a former senior policy adviser at the International Monetary Fund. He is the author of many books, including In Defence of Public Debt

Friday 16 September marked 30 years since ‘Black Wednesday’, when the pound was ignominiously ejected from the exchange rate mechanism of the European Monetary System. Not all anniversaries are occasions for celebration. This one certainly is not.