Image copyright harry_mckeown Image caption Harry McKeown with his £50 found in Leeds

An anonymous tweeter in San Francisco has sparked a trend that's starting to take off worldwide - the Twitter treasure hunt for cash.

Who wouldn't want to find an envelope stuffed with cash? That may explain why more than 250,000 people have started to follow the @HiddenCash account. As we reported on this blog, the account holder - who wants to remain anonymous - has been hiding money at sites across San Francisco, and leaving clues on Twitter.

Less than one week after that account tweeted its first clue, dozens of similar accounts have sprung up. Most are in the US - in Florida, Colorado, Texas and elsewhere - but the trend has started to go global. Nigeria, India, Hong Kong, the Netherlands and the UK all now have their own accounts.

"I saw it going viral on the internet, and I thought 'This is a really cool idea,'" says the man behind the new @HiddenCash_UK account, which was set up on Wednesday. He told BBC Trending that he plans to hide money-stuffed envelopes right across the country.

The first one - with £50 ($85) inside - was hidden in Leeds, and found by electrician Harry McKeown. He'd heard about the Hidden Cash accounts while watching TV at the dentist, and happened to be just five minutes away when he saw the first clue pop up on Twitter. "My friend said 'It will be a wind-up.' And I thought I'd look a bit stupid looking. But turned out it was legit," he says. "I was like 'No way!'"

Media playback is unsupported on your device Media caption Money has been found in various places after clues were posted in Twitter

The next envelope was hidden in Manchester. Another will be hidden in London on Friday.

Like the person running the San Francisco version, the man behind the UK one also wants to stay anonymous. He says he's relying on a series of close friends and contacts across the country to hide the money. So why is he doing it? "It's fun for me, and it helps people out - so it's a win-win," he says.

Reporting by Cordelia Hebblethwaite

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