This week, with the help of national treasure Joanna Lumley, Marks & Spencer launched its Shwopping campaign. The idea is to encourage people to bring old garments into stores when they buy new ones, to reduce the 1bn items chucked into UK landfill each year. The old clothes will be sold or recycled by Oxfam, which already offers a £5 voucher to people bringing old M&S clothes into its charity shops.

Lumley is no fool. "We women, I think, know in our hearts that we shouldn't chuck stuff away," she told the Telegraph. "I think young people have been encouraged to buy something, wear it for months and throw it out."

One is tempted to suggest M&S would achieve its aims better if it discouraged feckless clothes-buying, by specialising in more expensive investment items, made in Britain, like it used to. Or refrained from selling so much of its food in plastic packaging.

But all retailers want consumers to keep consuming. If they can market the idea that it's green to do so, they will. And "Shwopping"? It's an ugly word for a mildly dubious enterprise. I don't suppose there's much harm in it. But I can't help feeling it's not good enough for such enthusiastic endorsement from Lumley.