The Moss romance will only grow now she's 40

Kate Moss has set the standard in style for half her life. Photo / AP

Kate Moss turned 40 on Thursday. For more than half that time, she has - with great style, impressive tact and good taste - successfully sold her clothed and naked body to an appreciative fashion business and an admiring public. In the frivolous world she inhabits, where a season is an eternity, her endurance has been remarkable.

But 40 is a critical threshold in anyone's life. Victor Hugo said it marked "the old age of youth". So what do we make of her as she approaches middle age?

Kate, for all her epic visibility, is low-temperature, inscrutable. Her allure is magnified by her high-profile silence. And that is part of the appeal. Moss's personality is as cleverly protected as her body image is adroitly projected. She offers the spectacle of absolute thinness and what to do with it. Moss almost never gives interviews, but one of her few collected remarks is memorable. Nothing, she once said, tastes as good as skinny feels.

"Icon" is an abused term, but the prominence and power of Kate Moss's image allows its legitimate use. An icon was a religious stereotype, often mass-produced, but nonetheless conveying real meaning to a devoted congregation in search of succour and inspiration. We are that congregation. Kate Moss, via Calvin Klein and other leaders of the religion that is fashion, tells us what an elegant woman looks like. And to the men, that emotionless stare simultaneously says: "Not in a million years, sunshine."

Future historians will surely note that Moss came to prominence in the late '80s at a time when "design" evolved from being a technical conversation in a drawing office, or the province of a few tastemakers, to a fashionable topic. It's significant that she comes from subtopian Croydon, which Simon Jenkins described as an "off-centre office location ... awful to behold". I'll say one thing about lower-middle England, though - it's a very good launch pad.

The year after Moss was scouted as a child in John F Kennedy airport, the French high-concept photographer Bettina Rheims took her portrait. The picture shows a salacious innocent, naked from the waist up, with a tumble of curls. The caption says: "Kate Moss, Londres, 1989". It was The Face, a magazine that captured all the point, dash and silliness of the style-crazy moment, that championed her.

Another question historians will ponder is: precisely when did the status of the fashion model change? There was a time when superannuated models, with too many bunions for spike heels and too many wrinkles for a cosmetics shoot, retired away from intrusive lenses to a cottage in Wales and began to paint or raise endangered species, while wearing easy-going kaftans.

Instead, in confirmation with the cultural directives of the '80s that canonised objects, Moss leapt the species barrier and, at a time when her peers had retired, ceased being merely a slow-eyed, knock-kneed, snaggle-toothed animate coat-hanger and actually became a subject for art: a muse, indeed. She was a designed object and artists competed to capture her essence. The hyperrealist Chuck Close made Kate Moss daguerreotypes. In 2002, Lucian Freud painted her skinny form draped on a daybed. One of his last works of art was a tattoo he gave her. She has been sculpted by Marc Quinn.

The control and direction of Kate Moss's image is masterly. Like a grande horizontale of 19th-century Paris, she suggests erotic pleasure, but is in absolute control of access and has her fingers decisively upon the on-off switch.

It's not all about sex but, if we are honest, quite a lot of it is. Yet there are paradoxes in the Kate Moss sexual proposition. She has been photographed nude since she was 14 or 15 in images that combine absolute frankness with absolute dignity. She is ludicrously sexy, but not at all smutty. A naked Kate Moss is an affirmation of something lovely, not an invitation to sordid and drooling venery. You can check this in last month's 60th anniversary of Playboy, in which Moss did an ambitious session with the photographers Mert and Marcus, the Botticellis of high fashion.

Kate Moss is beautiful, too. Of course, beauty is notoriously difficult to define. Moss's flaws (those teeth and knock knees), in swaggering combination with exquisite bone structure, exceptional poise and a genius for reinvention, place her at that very median point between plain mediocrity and boring perfection.

In our own time, the Harvard literary critic Elaine Scarry says we know something is beautiful if we want more of it. And no one has yet tired of Kate Moss. So what do we think of her legacy and her prospects on the other side of 40? I dare say trashing hotel rooms will soon be forgotten. Great to remember Kate in lacerated denim shorts and wellies at Glastonbury, but the generalities are more important than the details.

She has used her body to create a world of legend and romance. That's not design, that's art. So far as I am concerned, we want to see more of the middle-aged Moss.