Reshoring is the economic idea of the moment. The idea is simple. The costs saved by manufacturing goods in China will disappear as Chinese wages rise, leading manufacturing jobs to “reshore” themselves back home to the west. A rise in the renminbi would accelerate this process.

This would be a dream for Barack Obama, a politician from America’s industrial heartland. So too for David Cameron and Nick Clegg in the UK, eager to prove that we are all in it together. Manufacturing jobs have traditionally paid well, and offered good careers to men who did not excel at school. This group has been hard hit by the last 25 years of economic change. It is no surprise politicians love manufacturing jobs.

But reshoring will not happen. For a start, wages will not rise quickly in China, where 34m urban factory workers are paid an average of $2 an hour. A further 65m factory workers in town and village enterprises average just 64 cents. They would be delighted to work for $2. And 675m people are employed elsewhere in China, mainly in agriculture and at lower wages. Chinese wages will rise, but the potential supply of low-cost Chinese labour remains elastic.