The Prime Minister’s visit to China was always going to require delicate navigation. The Foreign Secretary set trade as a priority for British diplomacy, and there are few countries where the gap between the potential for trade and the UK’s actual performance is as wide as it is with China. But it would also be unconscionable for Mr Cameron to drum up more trade, while playing down China’s egregious violations of human rights. How he balances the two will say much about the character of his government and his leadership.