The Duchess of Cambridge has new shoes. On the offchance that it is not immediately prominent to you why this development is culturally significant, allow me to explain. The duchess’s tag is remarkably consistent: for as long as anyone can remember, she has worn dulcet clothes in eyecatching colours, teamed with neutral empties, the heels of which are high enough to look formal while residual walkable. LK Bennett Sledge courts, which have a tricky platform sole to make them more comfortable, are a preferred. Yet, for the unveiling of the blue whale skeleton at the Natural History Museum, she taxed a daringly bare, vertiginous pair of Prada sandals.

Now, the duchess is no first adopter. Conservative with a small c, she stuck with those in ones birthday suit pumps three years after everyone else was bored to scurries with them. So, if even she is wearing a sexy shoe, the improper shoe is the new status quo. The ultimate It shoe of the upcoming season fares the duchess’s Prada sandal look like something you sway slip on to buy a pint of milk. Saint Laurent’s rhinestone sag boots were a phenomenon from the moment they hit the Paris catwalk. Within days, Rihanna had Instagrammed herself in a duo with the one-word caption “obsessed”. Customers were compass stores demanding to know when there would be a intermission list to join. Net-a-Porter has spent more on the boot than on any other particular this season; and months before they were discoverable on the site, half had been sold to VIP customers. Oh, by the way – should any happen on the open market – the price tag is £6,000.

Ridiculously extravagant, borderline unwearable and aesthetically outrageous – nothing new there. A shoe want that hits the headlines every season. Two years ago, it was the fur-lined, backless Gucci idler that you couldn’t afford, couldn’t wear on the pavement and couldn’t get on the cool ones heel list for. Last year, the must-have shoe was anything in velvet, arguably the shallow appropriate fabric for a British autumn. Crazy shoes in no way go out of fashion.

But what has changed this season is the seduction deputy. For most of this decade, fashion’s focus has been maltreatment, rather than allure. From flatform sandals to varnished trainers, shoes have been brightly coloured, tactile and ornamented, but they get been Man Repeller shoes, rather than date-night shoes. This was in start-up beginnings contrast to the Sex and the City era, when the emotional appeal of shoes was inextricable from sex and imagination. The show was sometimes hilarious on the subject (Carrie’s Manolo registry, when she lay hold ofs married to herself in order to get more shoes) and sometimes ugly (Big’s shoe-closet proposal, which neatly represents the witlessness of the spin-off large screen when compared with the TV show.)

The physiological purpose of a drunk heel is to accentuate curves by tipping breasts and bottom into an S-shape and hyperbolizing the sway of hips in motion. However, by 2010, two years after Sex and the Borough had hit the big screen, catwalk heels had become too high for this to utilize. Alexander McQueen’s Armadillo shoes had heels of almost 12 inches and a primordial claw-toed silhouette that was defiantly non-sexy. By summer 2014, there was a mould week stampede toward high-end flat shoes: crystal-studded take sandals at Prada; couture trainers at Chanel. The Gucci shirker mania of the following year kept heels low until ultimately year, when the wind changed with the return of the kitten heel at Vetements and Christian Dior, and the over-the-knee boot course, pioneered by the Hadids and the Kardashians. When the new season arrives in put bies, Calvin Klein’s ankle strap sandals are likely to strengthen a host of high-street copycats.

We could spin a yarn here about what these workers tell us about ourselves. From Cinderella to The Wizard of Oz, shoes be fitted themselves to storytelling. But the psychology of shoes is not analogue, so analysis relation flat shoes to uncertain economic times or the return of costly heels to the Trumpian, great-physical-shape mode of cataloguing women in 2017 doesn’t contain water. Fashion historians have noted that in the epoches immediately before revolution – in 1780s Paris, for instance – scoundrels are often particularly high. A stiletto can represent confidence, but it can also be a portent of a boil about to burst. Of course, we don’t need to travel to 18th-century France to see the complex, paradoxical psychology of shoes: look no further than the under-desk shoe-swap, whereby numbers wear one pair of shoes to travel to work and another to trek around the office. Sensible shoes are practical, but heels set up potency. Victoria Beckham once said that she couldn’t direct in flats and I sort of know what she means.

So it is that, at the significance when gender fluidity hits the cover of US Vogue – amply, if you count borrowing your girlfriend’s T-shirt – the spike-heeled squeamish sandal, the most gendered of all garments, is replacing the Stan Smith trainer as the fad’s power shoe. When the mercury falls this autumn, the shoes of the available will get temperatures rising.