In his blackly humorous book, Mr China, Tim Clissold relates how he and a US business partner blew some $400m in the 1990s buying mainland companies that turned out to be duds. The pair would have a quite different problem today. Chinese companies are generally better run than a decade ago. But they are becoming harder for foreigners to acquire.

Lengthening official delays in approving deals, combined with a political backlash over foreign companies' growing role in the economy, have put international investors on guard. China's door may still be open, but those waiting outside are less sure of a welcome than even six months ago.