From a human perspective, it is easy to understand the reluctance to face these numbers. It is hard to avoid the conclusion that millions of people have been deprived of their freedom, and millions of children have had their education gravely damaged, for little demonstrable gain. Who wants to admit that they were complicit in this? But what one American judge called the “laboratories of democracy” have conducted their experiment — and the result is increasingly clear.

Exactly why it turned out this way is harder to explain, but perhaps the “noble experiment” of the 1920s in the US can offer some clues. Prohibition didn’t win because the freedom argument prevailed. Nor was it because the substance itself had become any less harmful to people’s health. The reason for the eventual demise of the alcohol ban was that it simply didn’t work. No matter what the law said, Americans didn’t stop drinking alcohol. It simply moved from bars to “speakeasies”. People learned to brew their own spirits or smuggle it in from Canada. And the American mafia had a field day.

The mistake the American authorities made was to underestimate the complexity of society. Just because they banned alcohol did not mean that alcohol disappeared. People’s drives, desires and behaviours were impossible to predict or fit into a plan. A hundred years later, a new set of authorities made the same mistake. Closing schools didn’t stop children meeting in other settings; when life was extinguished in cities, many fled them, spreading the infection to new places; the authorities urged their citizens to buy food online, without thinking about who would transport the goods from home to home.