Like certain indigenous seed pods, the mouths of policymakers seem to be opened by South Africa’s heat. At the recent summit there for finance ministers and central bankers of the 20 most industrialised countries, participants had plenty to say about currencies. Jean-Claude Trichet, president of the European Central Bank, spoke of the dangers to global growth from “disorderly” currency movements, having recently described the euro’s appreciation as “brutal”. China’s central bank governor said that a sharp rise in the renminbi would “kill China’s growth”. Before the meeting started, Hank Paulson, US treasury secretary, was reiterating his country’s strong dollar policy.