Criss-crossing Beijing in the Chinese capital’s cheerfully coloured and slightly clunky taxis, it is easy to see what European Union negotiators mean when they say the Chinese give them the run-around.

Since I arrived on Sunday, I have taken, or tried to take, seven taxis. One got me to the correct destination. Two took me somewhere completely different, and four refused even to let me hop in.

My 14 per cent success rate left me feeling smaller than a terra cotta warrior from Xian, but I’ll wager it will be higher than the visiting Europeans achieve this week.

Nicolas Sarkozy, Peter Mandelson, Jean-Claude Trichet, Jean-Claude Juncker, Joaquín Almunia and the rest of them can spout till they’re blue in the face about the supposedly undervalued renminbi, but they might as well be talking to the Great Wall of China.

What is more, the Chinese have a point. When you look at China’s explosive export growth, it is difficult or even absurd to make the argument that it is all down to the renminbi’s exchange rate. Juncker says the currency is 20 to 25 per cent undervalued against the euro, but if it went up by that amount overnight, China’s export machine would still churn out vast volumes of goods at prices Europeans love.

Mandelson, the EU trade commissioner, appears to grasp that. During his visits to China, he therefore tends to dwell more on issues such as restrictions on European access to the Chinese market and poorly protected European intellectual property rights. But when he made a speech on Monday about food product safety and included some criticisms of the Chinese position, the fearsome vice-premier Wu Yi, China’s top trade official, said icily that she was “extremely dissatisfied” with his remarks.

Not all is wrong in the EU-Chinese trade relationship. How can it be when the EU is China’s biggest trading partner and when trade, measured in dollar terms, is up more than 20 per cent so far this year?

Still, when a reporter asked Mandelson how long his patience with China would last, he replied: “My patience is not exhausted, but I can no longer suffer in silence.”

China, be warned. Any more of this funny business on trade and Mandelson may snap his chopsticks in frustration.