Prince William braved freezing temperatures to take part
Prince William has spent a night sleeping rough in an event organised by a charity for the homeless.
William slept in a sleeping bag near Blackfriars Bridge in central London last week, as part of his role as a patron of the Centrepoint organisation.
He said he could not "even begin to imagine what it must be like to sleep rough night after night".
Clarence House said a "small element of security" had remained with the prince during the night.
Prince William said the experience had deepened his understanding of homelessness.
"Poverty, mental illness, drug and alcohol dependency and family breakdown cause people to become and then stay homeless," he said.
"Centrepoint's work - along with many other organisations' - in tackling these fundamental causes is desperately important if we are ever to end homelessness in this country."
The prince was joined by the charity's chief executive Seyi Obakin, who said they were almost run over by a road sweeper vehicle.
Mr Obakin said: "For me, it was a scary experience. Out of my comfortable bed. Out there in the elements. Out there on an extremely cold night, with temperatures down to -4C.
"And it was the same for Prince William. But he was determined to do it as patron in order to raise awareness of the problem and to be able to understand a little better what rough sleepers go through night after night."
The challenge arose after William gave a speech to mark Centrepoint's 40th anniversary this year.
They were joined in the event by the prince's private secretary, Jamie Lowther-Pinkerton.
Mr Obakin told his charity's website: "We took as much precaution as possible - finding a relatively secluded spot in an alleyway, shielded partly by a collection of wheelie bins.
"But there was no shielding from the bitter cold, or the hard concrete floor, or the fear of being accosted by drug dealers, pimps or those out to give homeless people a 'good kicking'."
The group slept until 0600 GMT when the prince was taken on a tour of areas where people were sleeping rough in the West End of London.
He then went to Centrepoint's Greek Street centre where he cooked breakfast for a group of young homeless people.
A spokesperson for Clarence House, the prince's official residence, said: "Prince William, as patron of Centrepoint, was keen to help raise the profile of Centrepoint and experience a tiny bit of what it is like to sleep rough in the UK today."