Thrifty living: Chuck out your tinsel and get someone else's

We all know that bringing your box of old Christmas decorations down from the loft and reusing them is the greenest and cheapest way of embellishing your tree, but how about swapping them with someone else's old baubles?

London's Covent Garden, which has never struck me as the thriftiest place for Christmas shopping (or shopping at any other time), has managed to tear itself away from focusing solely on its Christmas luxury food market (where you can have your gifts wrapped by a woman who has gift-wraps for the Queen, and where the Twelve Days of Christmas will be marked with "four-bird roasts", hand-dived scallops, and specialist tea boxes). It has devoted one of its outlets free to Decoration Exchange, a sort of bring-and-buy bauble set-up. The idea is that you can bring along your old tinselly tat and exchange it for someone else's.

"I met a woman who had 10 boxes of decorations in her loft!" says Judy Berger, founder of online swap-shop site Whatsmineisyours.com. "Now she can bring them down and swap them with what we have here! Everyone says we have a disposable society, but this turns all of that on its head. And if you just want to change your decorating theme this year, it's such a cheap way of doing it."

Decorating theme? Surely no one outside the pages of Elle Decoration actually believes in having themed tinsel? It would seem not. "For example, last year my theme was pink and silver," continues Berger excitedly. "This year it's going to be Gothic. So I'm going to bring all my pink stuff down and swap it for dark baubles with flocking. Perfect!"

Speaking as someone who barely gets through the travails of filling four Christmas stockings for children of varying ages and genders, plus one for the dog, organising annually churned themed decorations seems a bit high-end for me, but the overall notion is a good one.

"Look at this!" cries Berger, proffering three glittery reindeer. "We valued this, which I believe is a vintage Paperchase decoration, at 5. So the person who brought it along handed it in, then went to the 5 box, and picked up a new decoration." Your decorations will be valued on the spot by Berger and her team, from 1 to 10. If you bring in enough stuff, you will be able to take home a whole new stash of gaudy nonsense with which to garland your tree. If you are lucky, you might even have a celeb quotient blended into the money-saving schtick, which seems like a contradiction in terms, but that's Christmas for you.

"Katie Melua came and gave us this," sighs Berger, showing me a "vintage" box of three signed Christmas bells from the celebrated singer. "I think we might auction this. Elle Macpherson has promised to bring something down for us as well." Just imagine: this year your Christmas theme could be celebrity, the highlight of which shall be swathes of tinsel, touched by Elle Macpherson!

Currently, each swap box is full of new donations from Christmas traders; glass baubles, tiny spacemen and rather jolly hangable Santas which you will get for your swap. As the weeks progress, however, Berger hopes that they will gradually fill up with a huge variety of muddled and bizarre decorations as people go up into their lofts and realise that, indeed, they cannot face yet another Christmas staring at those glass icicles, circa 1988, or those dreadful pink baubles from last year's sale area at Tesco.

Even if you don't have anything to bring, you can buy some of the cast-offs, as the Decoration Exchange will offer swap-or-buy on everything, with funds going to Camilla Batmanghelidjh's Kid's Company, a charity that cares for exceptionally vulnerable children in London.

There's no question, but the whole venture has feelgood written right through it, and Berger is as pleased with her donated Covent Garden unit as she has any right to be. We start chatting about swaps on a grand scale, and before I know it, we have gone through clothes, records and books right up to the moment when she has negotiated swapping a sun-kissed weekend in her Cyprus flat for one in my Paris love-nest. She's that sort of woman. "It's a bit like that man who managed to trade a paper clip for a house," says Ellen, Berger's assistant. "Hmm," sniffs Berger. "I happen to think that was just invented." Maybe.

But the Covent Garden initiative seems like the real thing, a welcome advent of cashless trading in the midst of the craven till-ringing commercial emporia that constitute the capital's West End in December.