It is not the first time Angela Merkel, the German chancellor, has complained about ultra-loose monetary policy in the Anglo-Saxon world. But when attacking the European Central Bank yesterday for its planned purchase of cover bonds - an unconventional way to help financial markets recover - Ms Merkel broke an unwritten ban on German leaders commenting on monetary policy close to home. The message, it seems, is that Berlin is more worried than people had assumed.

The chancellor is not just concerned about the long-term inflationary potential of excessive monetary loosening. Her main concern is that expansionary fiscal and monetary policy being deployed across the industrial world could lead to future bubbles.