WE SHOULD LISTEN more to that great seer and philosopher Elizabeth Hurley. “Fashion has no mercy,” she’d intone plummily on the TV programme Project Catwalk, as she cast some wannabe Armani back to changing-room duty. And fashion has no morals either, no conscience, no heart. You might as well implore arms traders to have compassion for landmine amputees as beg fashion designers to ensure that their scrawny teens have eaten a proper breakfast.

Fashion is a multibillion-pound industrial engine that generates desire in women for an impossible ideal of beauty. That is how it flogs clothes: maybe if we shell out for that £300 dress we will attain beauty, for a flickering moment, before fashion sweeps imperiously on.

And with the aesthetic currently calibrated to skeletal, no one will defy it, not even our supposed cuddly national treasure Sir Paul Smith who, at his London show this week, sent a Belsen- survivor manqué down the catwalk in a scarlet silk camisole. When asked why, he shrugged and said he would use heavier girls if the model agencies sent them, as if he — their paymaster and a vast global brand — could not call the shots.

But he chose not to. Because this season, size 0 (equivalent to a British size 4), is “The Look”. Older, larger models could render his collection dated and frumpy. He weighed principles against profit. And, hey, guess which won?

Yet I cannot get overly agitated about the super-skinny look. I will not be joining the ill-fitting skirt-suited ranks of women MPs calling for a school nurse to weigh and measure models, calculate their BMI, then send them off with a healthy, yet calorific snack. In the mid-90s The Look was “heroin chic” — not merely skeletal, but skeletal junkie — and yet millions of ordinary young women did not suddenly spark up crack pipes. Not outside fashion itself anyway.

The size 0 is the product of a peculiar synthesis of showbusiness and fashion. It began when Hollywood actresses — the casts of Friends, Sex and the City and Ally McBeal — realised that to look svelte and sportive on screen, they must in real life be 10lb underweight. And in LA, where every girl dreams of stardom, this became the paradigm and dress sizes tumbled. This look is not about getting laid — straight men are repelled by boy-hipped bone-bags — but conveying your right to red carpet status. Moreover actresses have replaced models as fashion standard-bearers: to quote again our sage, Ms Hurley: “Being able to squeeze myself into tiny clothes is how I earn my living.” The Oscars have become the biggest catwalk show on earth.

But beyond California the size 0 has not taken hold. In New York this summer, I noted that women were lean and gym-trim, but there were few stick women. And in Britain, our only size 0 icon, Victoria Beckham, is ridiculed and told to scoff a few pies or risk losing her husband. Everywhere in London, I see teenage girls displaying their round bellies over jeans without giving a quarter-pounder-with-cheese for the diktats of fashion.

At least the size 0 is so obviously freakish and ugly that it is less likely to inspire envy in adolescent girls than horror and pity. When Christie Turlington and Cindy Crawford ruled the catwalk, it was tempting to believe just trying harder in Tums and Bums class would transform you into a glowing amazon. Teenage girls with a predisposition to anorexia will starve themselves whether models are scary-thin or just healthy-slender.

Mostly women don’t want to look at imperfection. I edited a mass-market magazine once, whose average reader was a good few cakes north of Erin O’Connor. I published fashion modelled by (gorgeous, perfectly proportioned) size-16 models alongside the conventional size 10, only to hear readers in focus groups poke cruel fun at the bigger models’ thighs.

Fashion is about exclusivity and any sucker can be fat. The upmarket designers do not omit to make larger sizes for economic reasons — as they often claim — but because they do not want porkers parading about degrading their brand.

Anyway the size 0 moment will pass soon enough, just as the anti-fur moment passed a season after the Peta campaign persuaded supermodels to pose naked, when Naomi Campbell was photographed in a silver fox coat. Well — duh! — fur was hip again, what did we expect? Fashion people do not hold principles, they merely wear them. They see no reason why Kate Moss, a recovering cocaine addict, should not design for the teenagers who flock to Topshop. Fashion is full of amoral aesthetes who would march down the catwalk dressed as storm-troopers wearing jackboots made from Rwandan orphans if that was deemed The Look.

As for the models: well, they’ve always subsisted on Evian and Marlboro Lights. But rarely for long, since their careers last just a few seasons before designers demand new blood. And most of them are slim because they are just incredibly young, their womanly hips and breasts barely formed. It would be more practicable to insist upon a minimum age — 17 perhaps — rather than a minimum body mass. But what fool would let a 15-year-old daughter into a rapacious industry to be judged, rejected and preyed upon? At least the Thai villagers who send their girls into the sex bars of Pattaya need the money.

• SO CHILDREN who learn musical instruments are not just blessed with an enchanting accomplishment, they are, according to research, all-round super-brainier. This is dismaying news for the cloth-eared, tone-deaf breeders among us. Both my husband and I grew up in households where the ambient noise was Radio 4, unable to play a single note. We have passed on our lack of talent and musical enthusiasm to our sons. In part, I have always been disdainful of musical children after, years ago at a fancy dinner party, being compelled to watch our host’s offspring murder Pachelbel’s Canon and Fugue.

  But now, I find too late, that the musically gifted can more easily inveigle their way into popular state schools. If I had been told that when I gave birth, I’d have braced myself for a decade of cat-screech violin.

  But part of me secretly mutters: what’s so special about music? Why not a gardening scholarship or one for mastering Grade 8 on PlayStation2?

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