Imagine this. You turn up at Waverley or Piccadilly station. You ask for a ticket to your destination. You’re then told that you can’t have one. You were spotted jaywalking or have failed to pay a parking fine. As a result, the state has revoked your right to travel.

Something like this happened to thousands of people in China last year. The country is building a new “social credit” system that aims to assign points to people not only on the basis of their financial history (as credit reference agencies do in the West), but also their recent behaviour. This could include criminal convictions, as well as violations of more widely defined social norms: a shouting match in the street, or wisecracks on social media