For more than a month, John Snow, the US Treasury secretary, carried with him a closely guarded secret: that China would soon scrap the renminbi’s decade-old peg to the dollar. Last week, when he was quietly informed by Chinese authorities of their plans and precise timing for a revaluation and new rate regime, it came after a nearly two-year long campaign during which Mr Snow had faced intense criticism from Congress and US manufacturers over an approach that was seen as too slow in yielding results.

The unusual early warning from a generally secretive Chinese government helped ensure that the revaluation, finally announced last Thursday, would be a high point of what has sometimes been a rocky tenure for Mr Snow. By insisting that currency flexibility was in China’s own economic interests, and by stressing global concerns rather than narrow US ones, Mr Snow appears to have helped Beijing move in a direction the administration of President George W. Bush sorely needed to defuse rising frustration in Washington over what is seen as China’s unfair trade advantages.