If you’re keen to get your hands on a dress or bag worn by Alexa Chung or Daisy Lowe then Marks & Spencer is the place to head today. This morning the brand’s Marble Arch store is playing host to its first ever Shwop Shop, an in-house Oxfam shop packed with pre-loved pieces donated by some of your favourite stars.

The Shwopping initiative, which launched last year, encourages shoppers to donate their unwanted clothes so that they can be resold, reused or recycled rather than sending them to landfill. The face of the campaign, Joanna Lumley, was on hand this morning to open the store, and is even set to act as shop girl today. (‘It’s a risk,’ she told us, ‘because I can’t work out how to work the tills.’) We suspect that if you ask nicely she’ll even help you pick some pieces out.

Joanna, who has of course donated pieces herself, revealed that she has always been a keen charity shop fan. ’I always take bags of things in and come out having bought bags more. I’ve always donated things to charity shops but I didn’t realise that you can donate things that have holes in or that are stained because they can be recycled and turned into fabric.’

The Shwop Shop is open for two days only, and new pieces will be dropping into the store tomorrow. Just don’t forget to bring an unwanted piece of clothing with you – it doesn’t have to be from M&S – to shwop for your new buys.

The Shwop Shop is open on 24th and 25th January 2013 at Marks & Spencer, 468 Oxford Street, W1