It has, by all accounts, been an unusual summer. Not just the politics of it, nor the fact that the world order has been lurching from crisis to crisis. But also, crucially, the weather.

Having moved to London only a few months ago, I arrived just in time for a tremendous heatwave. Coming from California, I was surprised to notice the mania with which everyone initially greeted the sun, stripping off their clothes at the faintest ray. Peak heatwave syndrome struck in late July, when the BBC helpfully ran an article titled “Sun cream: how much to use and what to do if you burn”.

After several weeks of this, I realised the changes went deeper than the sunburn. Between the heatwave and the World Cup, everyone had become cheerful, friendly — downright sunny. “If we had four months of sunshine a year,” a British friend declared one warm evening, “it would change the national psyche.”