England didn’t just lose the World Cup. When it comes to male nudity, the country has also lost its sense of shame. Everywhere — on the Tube, in buses, on the streets, in the pub — men are striding around topless.

On Sunday in north Oxford I saw a man skiing topless, on roller-skis, with poles, down the Banbury Road. It’s as if Adam and Eve never ate from the tree of knowledge.

Yes, it’s very hot. And yes, in the summer of 1976, men took their tops off but only in particular situations: on the beach, on a building site or in their back garden. I must admit that I cycle with my shirt open in this heat. But because I’m moving at speed, no one is exposed to my mottled flesh for long. When my old prep-school teacher spotted me, half-dressed on my bike in Camden, I felt deeply ashamed and apologised to her.

But public shame is a declining commodity these days. Just look at Love Island — a major contributor to the public nakedness phenomenon. If people are prepared to walk about topless and talk graphically about sex on TV, no wonder the public imitate them on the street.

Male toplessness goes beyond the let-it-all-hang-out approach of a post-Christian, morally relativist society. Vanity is also to blame. Vanity — or showing off — used to be something to be ashamed of; whether it was showing off about how much money you had, how brilliant you were at your job or how polished your pecs were.

These days, self-deprecation is for losers — itself a horrible word that was never used in a more polite age. In a dog-eat-dog, money–obsessed, narcissistic society, subtle registers — like irony, sarcasm, overstatement and understatement — go unnoticed. People take you at your word, and you have to shout to be heard.

And so we become raging show-offs: racing Ferraris round Knightsbridge; wearing prominently labelled designer clothes, only to rip them off to advertise how much time and money our bodies have been spending at the gym. As Lauren Bacall once said, if only people exercised their brains as much as they did their bodies. In an age when men splurge more than ever before on clothes and grooming products, the national motto is ‘If you’ve got it, flaunt it’ — as one of the most disgusting catchphrases of the age has it; second only to ‘Because you’re worth it.’

The British used to be heroically unsure of themselves, particularly when it came to male nudity. Our sartorial guru was T.S. Eliot’s J. Alfred Prufrock who, in 1915, thought it daring to eat a peach and wear white flannel trousers on the beach. If people did get their kit off in the old days, it was to shock: like the fat men who went topless to football matches in the winter, cheerily mocking their own appalling physiques. The Femen topless protesters, who got going in Ukraine in 2008, are creating a shock too, to make a point about women’s rights; i.e. they’re not just vainly advertising how lovely they look.

The British used to strip to be amusing, as the male streakers at Lord’s did in the 1970s, and Erika Roe did so joyfully at Twickenham in 1982. And that was usually after a skinful: the new brigade of topless men are too vain to drink heavily — they’re deadly serious about their nakedness.

The traditional desperate British attempts to get a suntan made a certain sort of sense too. When Glasgow and Belfast get only 1,250 hours of sunshine a year while Rome gets 2,500 hours, it’s understandable that we roast ourselves bright pink on the rare occasions the sun shines.

The dry-roasted fatties, like the vanity-free figures in Michael Heath’s drawing, are still taking their tops off. But now they’ve been joined by a new brigade of buff, topless men who are too vain to go red. In the #MeToo age, they’re certainly not making sexual propositions to passers-by either. Disgusting as that would be, it would at least have a purpose, unlike this modern burst of sexless peacock-posturing.

Today’s male toplessness is a million miles from 1970s Tom Jones: shirt open, cheekily lodging a crucifix in his chest hair in a half-ironic, half-come-hither way.

The new toplessness is irony-free, sex-free and alcohol-free. It is the inevitable solipsistic result of treating your body like a temple: mens insana in corpore sano — an unfit mind in a fit body.