Chinese slang is full of off-colour terms for unlikely bedfellows. An “old cow nibbling on tender grass” refers to a couple with a large age gap. “Fresh flowers stuck in dung” points to a glaring gulf in looks.

Diplomacy is more genteel. But the incongruities between China and the EU, which on Friday concluded a summit with two communiqués expressing harmony on a range of matters, go well beyond age and appearance.

One is an ancient civilisation that insists on unity above all, the other a recent bloc of 28 often-dissenting countries. The authority of one flows from a single revolutionary party, while the other is bound by international law, due process and shared democratic values. Both rail against protectionism in global trade but mean different things when they speak on the topic. On strategic matters, especially Beijing’s assertiveness in the South China Sea, the two are poles apart.