W hen Angela Merkel ended a long and otherwise unremarkable speech about economic policy this week with a vitriolic attack on the world's three mightiest central banks, the German chancellor was writing a minor chapter of her country's political history.

No previous chancellor had dared attack their, and others', central banks so frontally - saying the US Federal Reserve, Bank of England and European Central Bank should all row back on their unconventional recent ways of propping up economies. Yet when the response came, Ms Merkel appeared perplexed. "They completely overreacted," she told an aide a day later as she scanned the front page of Thursday's Financial Times, which proclaimed: "Merkel mauls central banks".