Superstar record producer Nile Rodgers described the Duke of Cambridge as "really, really cool" as he picked up a special award for his charity work to help disadvantaged youngsters.
Rodgers, a producer, songwriter, musician and composer, who has worked with everyone from David Bowie to Diana Ross and Pharrell Williams, received the Centrepoint Youth Inspiration Award from William.
It was a highlight of a special fundraiser and awards evening in aid Centrepoint held in the grounds of Kensington Palace.
Rodgers, who joins previous winners including singer Jon Bon Jovi and tennis star Novak Djokovic, was honoured for his work in setting up the We Are Family Foundation in the wake of the attacks September 11.
It helps support and mentor creative youngsters.
William made a good first impression on Rodgers as they met for the first time ahead of the fundraiser which aims to raise £1.5 million.
Rodgers described William as "really really cool and very impressive".
Rodgers also said that helping the homeless is close to his heart as he was once homeless himself.
He said: "I am here to support the cause. I was homeless myself as a teenager. Even though I look upon it with a certain degree of romanticism, the truth is that I had a lot of support.
"I was on the street but thank God someone took me in and I had a place to go. In New York at that time there were not many opportunities for a person who was homeless - it was really tough.
"I was rescued by a woman who said 'I let Nile sleep on my couch until he could stand on his own two feet'."
William, like his mother Diana, Princess of Wales previously, is patron of Centrepoint which supports young rough sleepers.
Dame Joan Collins plus William's cousins Princess Beatrice and Lady Kitty Spencer were among the guests.
Lady Kitty said she is not nervous about sleeping out in two weeks time because "it is all part of supporting" Centrepoint.
Lady Kitty is following in William's footsteps and sleeping out for the charity.
William spent a night sleeping rough under Blackfriars Bridge in 2009 as part of Centrepoint's 40th anniversary celebrations.
Lady Kitty, who is sleeping out in two weeks, said: "It's all part of supporting Centrepoint. Whether you're coming to Kensington Palace or doing the sleep (out) you're supporting Centrepoint. I've rounded up lot of friends."
Guests for the sit-down three-course dinner and awards ceremony paid more than £1,000 for the lavish event and the chance to rub shoulders with celebrities including actors and Centrepoint ambassadors Colin Salmon and Lisa Maxwell.
In his speech William said: "About this time a few years ago, for one night, I gave up the warmth and comfort of my bed, and tried sleeping on the streets of London. Of course, this was just one night: I was cold but safe, and I knew I had a home waiting for me.
"This Christmas as many as 25,000 young people will be at risk of homelessness. And remember this, behind that appalling statistic is a human being not much older than many of our children and grandchildren, who is alone, frightened and confronted with impossible choices."
Phil Collins, 65, was set to sing but dropped out at the last minute because he is having treatment for a septic toe.
He apologised to the 420 guests in a pre-recorded video where he said "because I am diabetic it is more serious than I thought".
His song Another Day In Paradise, which has become an anthem for the homelessness movement, was sung instead by Conor Maynard.
A Centrepoint spokesman said: "It is an iconic song which woke up the world to the issue of homelessness.
"Nights like tonight are pivotal for fundraising and time get the money we need so they can leave homelessness behind for good."
Ellie Goulding, Craig David and Dirty Vegas were among the acts who took to the stage.