London's burning! Well, quite warm anyway. And Londoners are in manic Mediterranean mode. For the past week you couldn't walk through the West End without tripping over the alfresco tables of leisurely lunchers, sprawled over the pavement with their pinot grigios. Soho's Old Compton Street felt like Barcelona's Las Ramblas. Hyde Park was a swath of roasting flesh and palpitating perverts. And the streets were heaving with fair-weather cyclists, their mounds of sweaty fat wobbling like blancmanges improbably balanced on bikes still draped with winter's cobwebs.

I don't envy the Ambulance Service. The medics must be on permanent coronary alert. But I can understand why nobody wants to fry on the Underground. Is it my fevered imagination, or is steam rising from the entrances of some Tube stations? And what subliminal message does that convey about the Dante-esque hell on the platforms beneath?

The British in a hot summer present a wonderful anthropological case study. We pass through four distinct psychological states. I call them suspicion, immersion, irritation and revulsion. Suspicion is easily explained. Our weather is usually as cloudy as an adolescent strop. So we instinctively regard any burst of sunshine as a flash in the pan. We dither for days before casting the proverbial clout. It's as if we think of the weather as a flirty disco partner: tantalising us with hot moves, only to turn cold if we enthusiastically start ripping off our clothes in anticipation of joys to come.

Then, however, comes immersion. Our reserve cracks; sun-frenzy takes over. People flock to beaches, parks, even outdoor swimming pools usually inhabited only by masochists of the most self-flagellating variety.

This euphoric interlude may last several days. But then the third state sets in: a strange, puritanical irritation. Shouldn't these people be working, instead of lying on the grass getting skin cancer? Who wants a lunch table next to a traffic jam anyway? Isn't the air oppressive? And (the greatest British trauma of all) if it doesn't rain soon, what will become of the lawn?

So, if the hot spell persists, finally there is revulsion. People start to hate the sun, detest the quasi-Californian skies, abhor the heat. You don't believe me? Well, perhaps that's because you are too young to have lived through the nightmare summer of 1976.

I'm not. I had just left university, failed to get a “proper job”, as my dad put it - he meant dozing in some obscure cupboard at the BBC - and had signed on as a council roadsweeper. (I flattered myself into thinking that I was the most over-qualified roadsweeper in London. It later transpired that a PhD was picking up litter half a mile away.)

But as it turned out, I had the best job in Britain. For ten weeks from June 23 to August 29, the temperature rarely dropped below 80. I leant on a broom, acquired the tan of my life, and dedicated myself to observing the womenfolk of the Costa del Finchley traipsing by in almost no clothing. Onerous work, but someone had to do it.

By contrast, anyone who had an office job suffered appallingly. In 1970s Britain, airconditioning was unknown. It was one of those fantastical, transatlantic gadgets that one read about in glossy magazines. So offices were stifling. But worse was waiting at home. Nights were unbearable. Nobody could sleep, yet it was too hot even to contemplate the most languid of bonks. And with sleep deprivation came moods that snapped like twigs.

There was more. Britain, one of the wettest countries in the Western world, had somehow contrived to give itself a chronic water shortage even before the heatwave started - mostly because we relied on pipes laid by the early Victorians, if not the late Romans. (We still do.) So the first and most draconian of all hosepipe bans was introduced. Gardens shrivelled into dustbowls. That made the mood in suburbia even more mutinous. All those national traits that we hold so dear - fair play, tolerance, humour, compromise - evaporated faster than the water in the reservoirs.

Hot, bothered and befuddled, folk started acting very oddly. The Wurzels went to No 1 in the charts with a song called Combine Harvester. Yes, people were that deranged. And in this atmosphere of frayed nerves and short fuses, punk music was born. I still maintain that, but for the wretched heat, Sid Vicious would have been Sid Quite-A-Decent-Bloke.

All of which raises an interesting question. Suppose that, thanks to global warming, scorchers like 1976 become the norm. Could we cope? Do we have the temperament for heat? I sense that the answer is no. National climate, I believe, does shape national character. But it does so over the course of millennia. The British are the way they are - phlegmatic, restrained, ironic - in large part because our climate has been damp, dour and undemonstrative for centuries. It would take thousands of steamy summers for us to become a hot-blooded, volatile, voluble race like the Italians or the Spanish.

So although we cheer when the sun comes out, and imagine that it's making us happier, our mental and spiritual equilibrium actually depends on our climate being more or less permanently autumnal. If we consistently had summers like they have in Rio, we wouldn't just grow bananas - we'd go bananas.

Mind you, I'd love a few more days like last week, before winter takes a grip. But only if I have my toes nuzzled in wet sand and my bum buried in a bulging deckchair. Of course, I guarantee that by the time I hit the seaside the climate will have swung from Saharan to Siberian. Still, that has to be better than the Wurzels going to No 1.