What... this old thing?

As the Princess Royal steps out again in a dress she first wore for the wedding of Charles and Diana, Fiona MacGregor salutes Anne's effortless style in recycling a vintage yet timeless outfit

WELL, well, well – one would never have imagined it. At the mature age of 57, the Princess Royal, a woman renowned for her love of jodhpurs and sensible shoes, has emerged as the prefect style icon for the late noughties.

As credit-crunch worries highlight the obscene conspicuous consumption of WAGS with their one-wear-only £5,000 designer frocks and everyone is prophesying impending doom if we don't start recycling, Anne's decision to wear the same dress to a royal wedding this weekend as she did to another regal marriage almost 30 years ago couldn't have been more fitting with the current zeitgeist.

Certainly the aristocracy have a reputation for wearing clothes till they fall apart, as countless mould-stained tweed jackets and labrador-chewed Barbours on castle coat-hooks around the country testify. As the princess has said previously when discussing clothes and throwaway culture: "Economy is bred into me. My parents believe that things are not to be wasted. That lesson does last."

Royal recycling is all very well, but even Anne – whose dress sense has generally been somewhat despairingly filed under practical or frumpy, depending on how kind the commentator – would have been hard pushed to get away with attending a Windsor family bash dressed in re-spun hemp.

However, whether she was aware of it or not, her Maureen Baker white and yellow floral-print wrap dress also captured perfectly the current trend for vintage fashion, which has crept from the burlesque club scene to the couture catwalk courtesy of the likes of Dita Von Teese and Dior designer John Galliano.

The dress Anne donned for the marriage of Lady Rose Windsor, 28, daughter of the Duke of Gloucester, to George Gilman in London on Saturday, was a late-1970s/early-1980s take on prettily printed, ultra-feminine post-war dresses – giving her two vintage looks for the price of one.

When she wore it the first time round, at Charles and Diana's wedding back in 1981, society magazine Country Life said the princess – then 31 – looked "stunning", adding: "Princess Anne's dress was one of the prettiest she has worn in public." And she looked pretty damned good at the weekend, too.

Of course, for most of us vintage is something we inherit, pull triumphantly from the back of a charity shop rail or (too often nowadays) pay over the odds for at a specialist shop. The fact that Anne was able to pluck something from her own wardrobe and look great in it three decades on not only gives lie to the fashion rule "if you can remember wearing that style the first time round, you're too old for it now", but suggests Anne has more sartorial nous than we've previously given her credit for.

That old adage may be true of street fashion (however good the princess's figure may be, we doubt she could carry off the fluorescent leggings and batwing jumpers that most of us associate with the early 1980s), but when it comes to classic elegance, as Anne has proved, it's not the case.

This is not the first time Anne has "recycled" her old clothes – although perhaps not at such a high-profile event – and, as she has said herself, "A good suit goes on for ever. If it is properly made and has a classic look you can go on wearing it ad infinitum."

Still, it takes a certain amount of confidence for a post-menopausal woman – especially one who probably thinks Restylane is the name of a 1970s showjumper – to head out in public in a dress she bought for herself at 31.

Those who admire Anne's determined disregard for the vagaries of designer perfection may like to believe that the princess wasn't considering the fashion implications of her old dress. But can anyone honestly suggest that any woman turning 58 next month (as Anne will), wouldn't feel surge of smugness at being able to fit comfortably into a dress she bought 30 years ago – allegedly a size 10, too?

She may be considered "the most down to earth" member of the Royal Family, but do we detect just a hint of the show-off in her choice of outfit? Well, good luck to her. All those who have sneered at her outdoor lifestyle and unglamorous horsey activities over the years may now have to sit back on their plump behinds and admit that years of early-morning rides and lugging heavy tack has given the princess a figure no amount of expensive liposuction and shaking about on Power Plates could achieve.

Not that we're saying she's perfect. Even on Saturday the shoes still left a lot to be desired (although one may have to forgive her this as – given the rest of her family's similar failing – one suspects some kind of podiatry genetic defect to exist in the female descendents of Queen Victoria, which forces everyone of them to resort to hideous footwear).

But fair play to Her Royal Highness: she's been green, frugal, stylish, displayed vintage trendiness and kept her figure. What more could we ask of a woman when it comes to being fashionable in 2008?

Well, there's one final, but vital ingredient for cool which Anne displayed in kick-ass fashion when she turned up in that particular dress on Saturday afternoon: an utter disregard for parental sensibilities and a youthful schadenfreude in watching their expressions of horror as you appear in an outfit you know they will hate.

Elizabeth and Philip must have been wondering what exactly their only daughter was trying to prove by turning up for the latest royal nuptials in the same dress she wore for Prince Charles and Lady Diana Spencer's wedding – one of the most disastrous matches in the history of the Royal Family. The great thing is Anne probably wasn't trying to prove anything. In the style of a true trendsetter, she wore it because she wanted to and because she could get away with it.

It was a two-fingered sartorial gesture of which the most fashion-conscious teenage rebel would have been proud. She may never be a catwalk queen, but when it comes to insouciant cool – Anne's style definitely rules.