Over the past year, the chorus of concern over Chinese protectionism has grown increasingly loud. Robert Zoellick, US deputy secretary of state, is the latest to raise his voice, warning last week that Beijing could no longer adopt mercantilist trade policies without incurring retaliation from its trading partners.

An assumption behind Mr Zoellick's threat is the notion that Chinese companies and government agencies uniformly favour protectionism and that western businesses are dependent on intervention by their own governments to thwart such efforts.