Peter Rhodes on lessons from history, a Christmas baby boom and how two plus two can equal 100

Funny how quickly our priorities change. An eco-activist on the radio was banging on about saving the Great Barrier Reef. Seriously, have we ever been less bothered about coral?

If the NHS tells the Great British Public to lose weight, they will get fatter. Tell them to exercise more and they'll exercise less. Tell them to drink less and they'll drink more. So was anyone really surprised when the advice: “Stay at home” was interpreted by some Brits as: “Head for Skegness and pile into the amusement arcades” or by some teenage school-leavers as: “Party, party, party!”? We claim to cherish the NHS. So why do we so often ignore its advice?

While politicians invoke the Blitz spirit of 1940, we should be aware that the willingness of Brits to do as they were told in the Second World War was based not merely on mutual goodwill but by fear of a clear and present danger.

In September 1939 the British public had been told to expect immediate air raids by German bombers, dropping high explosives and poison gas. That's why, in a matter of a few days, about 1.5 million British children were evacuated from cities to the countryside. It was the biggest organised movement of people in our history, a landmark in national life. What happened next is less well-known. By January 1940, the promised air raids had not happened and half of the kids had been taken home by their parents.

The lesson for today's planners, 80 years on, is that people will co-operate with self-isolation, shortages and personal spacing in the long term only if they perceive a threat. The old and infirm are already scared and compliant but some younger people don't seem to get it. They probably won't make the connection between socialising and contagion until their own parents and grandparents start falling ill.

We could try explaining to youngsters – and to older people who ought to know better - that if they sit closely with a few friends, they may think there are only four at the table. In virus terms, all the people they have met in the past week are also present, plus their friends, and their friends' friends. Four people meet up, but there are many more at the table. So two plus two equals 100. I bet they didn't learn that at school.

While the hotel and catering industry collapses, other industries will boom as staying at home becomes the new going out. Some supermarkets have reportedly doubled their takings. Firms supplying books, jigsaws and board games also seem likely beneficiaries of isolation. Internet providers are seeing a rush of new subscribers and, if all else fails, there is always the oldest indoor recreation of all. Expect a baby boom at Christmas.