At the inaugural Group of 20 summit last April, world leaders united to keep the global economy ticking over with a volley of emergency measures. The G20 finance ministers are gathering once again this week in London, ahead of a full summit in Pittsburgh later this month. This time round, their task is to work out how to withdraw those policies while avoiding crumbling back into crisis. They should pay attention to some of the prudent suggestions put forward by Gordon Brown.

First, the UK prime minister has proposed that the G20 should co-ordinate monetary and fiscal policy. This is shrewd. The mistake that politicians must avoid is the one made by the US government in 1937. Then, rapid fiscal tightening in a weak economy triggered a fresh lurch into brutal recession.