Catherine, Duchess of Cambridge, is a commoner-turned-royal, not a couture clothes horse.
She is no Kate Moss, Lara Stone or other supermodel whose professional life is devoted to modelling the latest designer trends on the runway or in glossy magazines.
Since marrying a prince, her job is with The Firm, not in the fashion industry, and she does it very well. American fashion identities who have criticised her this week for lacking style should step down from their six-inch Louboutins and get a grip.
''If you take Kate out of the royal family [and] put her on a street in New York, you wouldn't look at her twice,'' the fashion director for department store Nordstrom, Gregg Andrews, said in comments quoted by the British media.
The Elle fashion news director, Anne Slowey, said: ''Is she a style icon of the likes of a Kate Moss? Absolutely not. Is she in the public eye? Are people going to become obsessed with everything she wears regardless of what it is? Yes.''
It is precisely because Catherine is not immersed like Moss in the world of high designer fashion, which often delivers up trends that are unwearable in everyday situations, that she has had so much influence on what ''ordinary'' women wear.
Alternating designer brands such as Burberry with middle-market labels like J Brand, Catherine mixes high and low fashion in a manner that is both attainable and elegant. Dressing head-to-toe in designer wear will not buy you true style, but the duchess has it in spades.
By favouring longer hemlines, more structured silhouettes and discreet accessories, she has ushered in a new, ladylike aesthetic for women of her age and beyond to aspire to, and for that we should be grateful.
The irony of scathing and self-centred criticisms by America's fashion police is that Middleton's glossy locks and pulled-together looks are far closer to those of New York's Park Avenue princesses than the undone, quirky style of London ladies. It is also interesting that Catherine's critics hail from the Big Apple, which is known as the most commercial of all the international fashion capitals.
Like Michelle Obama, Catherine has had an enormous influence on apparel sales in what remains a depressed retail environment.
Since her engagement to Prince William last year, almost everything she has worn has sold out within minutes, such as the nude Reiss dress she wore to meet President Barack Obama at Buckingham Palace in May. As soon as pictures of her wearing it appeared, the British retailer was selling the $316 dress at a rate of one a minute, until the Reiss website crashed after traffic increased 500 per cent.
It is also amusing that the snipey comments about her style come from the country that billed the gaucheness of Kim Kardashian's nuptials as ''the American royal wedding''. The reality TV star had no less than three Vera Wang dresses created to wear for the embarrassingly ostentatious occasion, and a mother who looked like a Christmas tree in another one.
The Duchess of Cambridge opted for a single Alexander McQueen dress at her wedding that drew favourable comparisons with Grace Kelly.
Its elegance and subtlety perfectly summed up Middleton's style, whose understated grace Americans like the Kardashian clan could learn a lot from.
Georgina Safe is The Sydney Morning Herald's fashion editor.
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