For a decade, I lived in a leafy Shanghai neighbourhood known for unlicensed street vendors who sold barbecued lamb kebabs, knock-off DVDs and (often) hashish.

Local police long tolerated their presence, usually in return for DVDs and kebabs. But eventually, as the neighbourhood trended upscale and orderly, the stalls and vendors were pushed out, victims of China's often-brutal bid to rid its streets of informal businesses and the headaches they created.