A Twitter account that undercuts touts by allowing music fans to exchange tickets for sell-out shows at face value has become one of the UK's fastest-growing businesses.
London web designer Richard Davies set up the @Twickets service after spotting a fan offering last-minute tickets free of charge on Twitter, rather than see them go to waste.
Davies guessed there were many other tickets going begging among fans who found they could no longer attend shows they'd booked to see.
He established Twickets in 2011 to pool fans' spare tickets. The concept, whereby all tickets go at face value or less, spread by word of mouth.
Last week a Twickets iPhone app sold 30,000 downloads. The site retweets all offers to its 13,000 followers, adding a Twitter hashtag to the post.
Some 45,000 spare tickets have changed hands on the site, with half of all tickets advertised finding a buyer.
Last week, tickets for sell-out shows by Kanye West and Dave Grohl were available for £60 or less on Twickets, while other secondary ticket sites such as Viagogo and Seatwave were charging up to £200.
"People are sick of having to use the secondary market to buy overpriced tickets," said Davies, who runs Twickets at no profit.
"We want to erode that market. We might find ways to monetise Twickets in the future, but the mission is simply to ensure that empty seats are filled."
Labour MP Sharon Hodgson has endorsed the company as part of her campaign against touts.
"Fans are being squeezed out of gigs and shows thanks to unscrupulous touts exploiting the talent of others," she said. "Twickets is what the secondary market should be about: true fans selling to true fans at face value."
The exchange, conceived when Davies managed to obtain a last-minute ticket to see Lykke Li at the Roundhouse on Twitter, has expanded to include train and ferry tickets.
The company currently only operates in the UK, but Davies has plans for growth.
"We hope to expand to Ireland next," he told the Independent. "People have contacted us in New York saying they want to introduce it there."