Invitations to the first official banquet for Wen Jiabao, the Chinese premier, were in short supply last December in Washington. One of the few business leaders to receive one was Warren Staley, chief executive of Cargill, the largest private company in the US. He delined.

"You don't get to meet anyone [at these events], so I said I would send someone. So they said: 'If it was a smaller lunch?' There were about 30 of us and I had a chance to talk to him," says Mr Staley.