Steps to ageing gracefully

Dressing well in your forties is about making the best of what you have, not competing with twentysomethings.

JK Rowling's gold platformed Gladiator sandals.

As pictures began to filter through from the long-awaited Harry Potter and the Half-Blood Prince premiere in London, the big red-carpet story was a somewhat surprising one. Emma Watson? Nope: she looked gorgeous, young, fresh and appropriately dressed (until her vintage Ossie Clark wrap frock blew aside revealing a little more than she had bargained for). Bonnie Wright? Well, the actress who plays Ginnie Weasley in the films is looking like a serious contender as the new Emma Watson, but that's a story still to be played out. How about Daniel Radcliffe? Well there's no doubt that his right on-trend suit was right off-taste but it merited only a passing glance in comparison with the evening's true offender: JK Rowling.

The beloved authoress, who came to fame at a youthful 32, has not made a habit of flashing her considerable cash on bling over the years, and has a reputation as a down-to-earth sort, unmoved by riches and adoration. Which made the rather terrifying Louboutins she was wearing all the more surprising. For one thing, they are remarkably similar to the gold strappy platforms worn on the same evening by Watson, 24 years her junior. They would not have been out of place if this was the premiere of Gladiator: The Musical, but on the 43-year-old Rowling, with her red-manicured toes splayed over the edges, they are rather (and we apologise, JK, for we respect your writing greatly), well, grotesque.

They could almost have been forgivable if they had not been combined with a saggy Philosophy di Alberta Ferretti frock featuring a neckline that would have been too décolleté for a 25-year-old, let alone a middle-aged mum who very admirably but very clearly has refrained from going under the knife. The metallic blue Marc Jacobs clutch did nothing to add gravitas to the look. Now perhaps this all sounds a little churlish, even petty: after all, we're supposed to be judging her on the quality of her wildly successful books. But her rags-to-riches life also makes her, if reluctantly, a role model for other women who dream of succeeding despite being slung on society's scrap heap because of their age, gender or other life choices. All eyes are on her. And her decision to dress like a teenager simply reinforces the modern ethos that no achievement can trounce the feat of looking eternally youthful.

Back in 2006, when Helen Mirren was first feted by Hollywood, much was made of her natural beauty, untouched, as far as we knew at the time, by scalpel or diet pills. In comparison to the skeletal, embalmed look popular among Tinseltown's ladies of a certain age, Mirren, now 63, has seemed like a refreshing vision of mature glamour. Her very confidence makes her beautiful. But even her example has failed to reverse the trend and she stands out among so many desperate-to-be-young women for whom the term "mutton dressed as lamb" could have been invented.

Take Madonna. This is a woman who has an incredible sense of style: her forties were marked by a series of classic-but-quirky, vintage-inspired looks and when recently spotted out and about with Stella McCartney, the 50-year-old wore a timeless white trouser suit and tweed trilby that no one could have objected to. She has a physique that many 30-year-olds dream of. Yet no amount of make-up, white lighting and yoga can rescue her from muttondom when she reveals sinewy legs and veiny arms in the micro minis, tiny shorts and high-cut leotards of her Sticky and Sweet tour, which launched last week.

It's not about wearing slippers and house coats. It's about remembering that the same rules apply whatever your age: dress to emphasise your good bits and hide the bad ones. If you look like Sharon Stone or Demi Moore, then fine - go ahead and wear a curve-clinging evening dress. In any case, those va-va-voom gowns are so full of boning and internal structure that everything is lifted and strapped in for the evening. But if you don't, then take some tips from the (admittedly still fabulous) likes of Mirren, Meryl Streep, Maggie Smith and Susan Sarandon. If you have batwing arms, wear sleeves. If your décolletage is less than perfect, go for a higher neckline or some cover-up jewellery. If you still have a tiny waist, emphasise it and keep everything else under wraps. And don't, whatever you do, compete with your younger companions by wearing gold Roman sandals with a two-inch platform.