Tim Geithner wants a strong dollar. Ben Bernanke wants a strong dollar. For all we know, Kate Middleton is rooting for the greenback. But what the US Treasury secretary and chairman of the Federal Reserve say they desire is not matched by their actions and they have got a weak dollar.

Weak, weaker, weakest. The Fed’s own measure of the dollar in real terms against America’s main trading partners shows it ended March at its lowest since it first traded freely in 1973. Since then it has fallen further, as Mr Bernanke’s supportive comments on Wednesday, far from shoring up the greenback, accelerated its decline. Worse-than-expected economic growth added to the dollar’s woes.

The power of the world’s reserve currency means many investors outside the US think in dollars. This is dangerous. Consider gold, at a new high of $1,538 an ounce on Thursday. This year, it is up 8 per cent. But in euro terms, gold has fallen 2.5 per cent.