As a child in my hometown, I often saw a rather beautiful elderly lady taking her daily walk up and down the street on which I lived. She caught my eye because, contrary to the peculiarly grannyish look worn by most of the town's old dears (shapeless Crimplene dresses, rectangular woollen coats, mink-coloured tights, stocky shoes and blue-rinsed curls), this woman walked tall (well, about 5-foot-3-inches with a highly polished cane to help) in a series of beautifully tailored, jewel-coloured trouser suits and matching trilbies worn at a dramatic angle. Sure, it was retro, but it was ineffably elegant.
Where was she going dressed like this in England's industrial Midlands? I don't think it mattered: the point was that she had never stopped making an effort.
In that, she reminded me of my own Gran, who always had a perfectly powdered nose, a pair of heels, pearl earrings and, if the weather demanded, a mink coat, at which my outraged teenage self would howl in protest while secretly craving just a tenth of the glamour she carried behind her cat's eye sunglasses.
But fashion's all about youth, right? The glowing skin, the slender figure, the energy and the innovation? Ever since 1950s teenagers first rebelled in the cause of their own independence, the industries of beauty and clothing have been finding ways to harness and exploit that prime-of-life vibrancy in ways that will make them more money.
They've gone in different directions, of course. The beauty industry is all about recapturing lost youth with Dh500 anti-wrinkle creams and pore-filling foundation - a sustainable, if ethically dubious, business plan because people getting older (as people will continue to do, in a globally ageing population) will blithely spend money to look younger.
Fashion, though, may have taken the whole thing a little too literally, with even the priciest clothes apparently designed to look wonderful on 15-year-olds who, let's face it, are pushed to make their Saturday-job wages stretch to a frock from Topshop. Problem is, those who have spent a few years building up to a comfortable income - the very people who might be able to afford those pieces - tend to be getting on a bit, in fashion terms. They like little details such as sleeves (to cover the not-quite-as-toned arms) and skirts that come below the thighs, and heels that don't require agonised tottering. The statues of the Roman Republic, in which realistically aged portrait heads were plonked comically on top of perfect, idealised, heroic bodies, are not great role models, and spandex should be avoided at 78. However, much of fashion tells us otherwise.
But equally, why should the grey dirham be spent on shapeless leisurewear and orthopaedic shoes? Look at the architects of the current fashion scene and you'll find few genuine power-wielders under 40: Karl Lagerfeld, Anna Piaggi, Franca and Carla Sozzani, Anna Wintour, Glenda Bailey, Giorgio Armani, Ralph Lauren. The designers in this list - Lagerfeld, Armani, Lauren - are among the most consistently high-performing names in fashion, thanks in part to their mystical ability to take a current trend and work it in a way that both delights the young, thrusting trendsters and offers flattering, fashionable, exquisite clothes for women of any age. You couldn't often say that about Christopher Kane or Henry Holland.
And it seems, perhaps because of that ageing population, or perhaps because of a recession that has hit the young hardest, that there is a swing back towards long-standing style over short-term fashion. One of 2011's most prominent fashion faces was a 90-year-old New York accessory collector, Iris Apfel, who in the past year has launched a jewellery collection for HSN, a collaboration with cult specs sellers eyebobs, and a make-up collection with MAC, and who has been the subject of a documentary by the Grey Gardens director Albert Maysles.
A mere youngster by comparison, the still-working 80-year-old model Carmen Dell'Orefice is the subject of an exhibition at the London College of Fashion, curated by David Downton, which has been extended into the new year to meet visitors' demands. The Sartorialist-style street-fashion website advancedstyle.blogspot.com has become a must-visit for its images of elderly style mavens around the world, but especially in the style-maven capital of New York.
With models such as Kate Moss (37), Stella Tennant (41) and the grey-and-proud Kristen McMenamy (47) still going strong on the catwalk, perhaps those teenage waifs will be able to wait a few years longer before being taken by the notorious child snatcher that is fashion.
Julia Robson is a London-based fashion journalist, broadcaster and stylist