Chief executives are swapping the boardroom for the cold outdoors as they sleep rough to raise awareness of increasing youth homelessness, and to raise money for charity.
Thirteen of Britain's top business leaders are spending one night outside in sleeping bags in Paternoster Square, in front of the London Stock Exchange. It is the first "CEO Sleepout" for Action for Children - and as part of the challenge the bosses must raise £10,000 each.
This means the charity is guaranteed to raise at least £130,000 to help vulnerable young people . The charity estimates that one in five homeless people is a care leaver, and that a third of young people who find themselves homeless will attempt to commit suicide.
Sir Tony Hawkhead, chief executive of the charity - who started his new job only four days ago - will be joined by 12 other chief executives, including ITN's John Hardie, Dell's Tim Griffin, and Barclaycard Europe's David Chan, as well as Mike Tobin OBE, founder of the event and head of TelecityGroup.
Mr Tobin said he came up with the idea for the event because he wanted to something "bigger" after being involved for seven years with Byte Night, the IT industry's annual sleep-out in support of the charity.
He said it was about raising awareness of the dangers young people face. "We have security but if you sleep in a tunnel, there's no security," he said. "Imagine how scary it is for a child."
The participants will endure the outdoors until tomorrow morning. Mr Tobin said they hoped the event would happen every year, while Mr Hawkhead said they hoped the numbers would double every year, with each chief executive inviting another to take part.
Sir Tony said it was important for an event like this to highlight "the big issue that homelessness is a growing problem, and there's a housing crisis".
Every year, the charity says, a t least 100,000 children and young people experience homelessness in the UK.
Sir Tony added: "In a narrow sense, chief executives raise money but it's also about using their reputation and personal clout to get other people's focus because homelessness has never been greater."