Who opposes urbanisation? No one, it seems. In the past decade, as hundreds of millions of people have left the countryside, the cheerleaders for more and bigger cities have grown increasingly numerous and vocal.

But is urbanisation really an economic panacea for the 60m who become city-dwellers each year? And will it deliver the returns expected across Africa and Asia?

The evidence should give us pause. Take the recent pollution in Chinese cities, or the worse levels of Indian ones. Then there are the ever greater numbers living in urban squalor – for example, the 60m to be added to slums this decade on top of the 825m already living in such places. And, despite being home to just over half the world’s population, cities account for more than 70 per cent of its waste and greenhouse gases.