‘Would Patsy Stone shwop?’ mused Joanna Lumley before the launch of the new Marks and Spencers sustainability initiative for which she is acting as global ambassador, ‘Poor old Patsy would be mistaken for a bundle of old rags and sent to the landfill herself if she dared to!’

Marks and Spencer in partnership with Oxfam today launch Shwopping, a new campaign which encourages consumers to reduce the amount of clothing waste produced in the country – that’s approximately 500,000 tonnes of clothing that ends up in landfills every year. To reduce this M&S are introducing a ‘buy one, give one’ shopping culture whereby consumers can give any unwanted clothing in-store, to be processed by the retailer and either sent to places in need, or shredded to be re-used in recycled clothing.

‘Everyone makes mistakes when buying clothing,’ says Lumley, ‘from the hardnosed housewife to the budding fashionista. But that’s why we’ve got to be just a little bit more conscious and taking the bag of unwanted things with us when we go shopping. We all mean to do it – now M&S are just making it that much easier.’

As Lumley explains, every delivery lorry that arrives to a store leaves empty, so it makes sense to utilise these trucks to transport unwanted things to be processed for re-use. All M&S clothing stores will accept unwanted clothing of any brand, all year round.

‘I was poor when I was young, so I got used to making things go round and round, looking after my things - make do and mend you know? But these days all that’s gone out the window so you’ve just got to try and be a bit more sensible. Buy something and leave something at the same time, you’ll feel more virtuous.’

If you want to find out more about Shwopping, check out the Swhop Lab, a series of talks and events being held at East London's Truman Brewery, where you can hear fashion insiders from Grace Woodward to VV Brown discussing the merits of sustainability.