American Woman star Sienna Miller has joined forces with Oxfam to launch the charity's #SecondHandSeptember campaign, raising awareness of the 'harmful effects fast fashion - clothes that are produced in high volume and at relatively low cost to the consumer - have on the planet', ahead of the UN climate summit COP26 in November.

Through the campaign, Oxfam is urging people to only buy second-hand clothes throughout September, as well as donating their pre-loved items, and Miller commented 'I am delighted to be the face of Oxfam’s Second Hand September.... These small changes can make a huge difference. And rooting around in a charity shop is like hunting for treasure. Be a magpie!'.