Clothes-swapping business Clotho, founded by Imperial graduates Vivien Tang and Caroline Wood, has been named joint winner of the Mayor of London’s Low Carbon Entrepreneur Prize.

The two women set up the sustainable fashion initiative last October; they met at Imperial and previously worked together as Chemistry lab partners.

Clotho provides a way for women to exchange their unwanted clothes for other items via an online shopping platform. The idea came about after Caroline lent Vivien a dress she’d never worn before.

When Vivien began wearing the dress frequently the pair realised that there must be loads of clothes hidden in the back of women’s wardrobes that are never worn, but never given away as they are deemed too valuable.

They set up the business from Vivien’s bedroom, choosing the name Clotho from Greek mythology, and have subsequently been developing the initiative across London and universities in the UK.

As part of the Mayor of London’s competition, Vivien pitched the business to a panel of judges at City Hall in London including Innocent Drinks co-founder Richard Reed, retired British sailor Dame Ellen MacArthur and ITV news presenter Charlene White.

After winning the top prize Vivien said “The competition was fantastic, and it was a great opportunity to meet other young entrepreneurs. I would definitely encourage anyone with a business idea to just go for it”.

The £20,000 award will be split between the two winners, who may spend it however they choose to expand their business. Clotho has also received a grant from the European Union’s Climate KIC initiative.

After another pitch in front of top fashion executives at a conference in London earlier this month, Vivien and Caroline secured further support from London-based retail and consumer start-up accelerator TrueStart.

Caroline said “We are really excited to be building a sustainable business that people love. Working with Vivien is so much fun ­ we are so thankful for all the funding and support we’ve receive and are now really looking forward to growing Clotho over the coming months”.

To take part in an exchange with Clotho go to www.clotholondon.co.uk, where you can arrange for your clothes to be collected. They sort through the items and estimate their retail value before sending you a credit voucher equal to the value of your submitted clothes, minus a 15% transaction fee. Use your credit to choose clothes from the shop, which restocks Sundays at 9pm.