Last May the Financial Times marked 10 years of independence for the Bank of England by praising both Gordon Brown’s bold decision to grant independence and the record of low, stable inflation that resulted – while warning that tougher times were ahead.

The tough times have arrived. The markets seem unsure of the Bank’s commitment to its inflation target. Its monetary policy committee, which sets interest rates, may have to make decisions that will cause the UK prime minister real trouble. Now, therefore, is the big test for the whole project of an independent Bank of England.