Our currency, your problem. In 1971, the US Treasury Secretary told the rest of the world it had to deal with a weak dollar. Nowadays, that sentiment could be expressed by the leaders of China, which has been able to control the level of the renminbi while pretty much ignoring complaints that the pace of revaluation is too slow. Japan, whose September intervention has been entirely reversed by the market, could only wish to be as successful.

Beijing’s attitude is far from unique. In countries big and small – Japan, Switzerland, Korea, the US and UK – a cheaper currency is seen as a painless solution to economic problems. But the forex game, unlike the real economy, is zero-sum. There has to be a match between gaining and losing countries .

There are no volunteers to be on the losing side. Eurozone leaders, who have seen the single currency rise 15 per cent against the dollar since June, will lead the grumbling at this weekend’s international summits in Washington, but politicians everywhere still think (reasonably enough) almost entirely of their domestic constituencies.