Stunned British tourists have told how they filmed Prince William cavorting on a club dance floor with two beauties.
Wills, 34, is seen gyrating with a blonde, believed to be Aussie model Sophie Taylor, and flirtatiously grabbing her cowboy hat and plonking it on his head in a Swiss club.
Royal expert Katie Nicholl said: "It's safe to assume that Kate will be far from happy about this."
Other clips show William, who had left wife Kate at home to go on a lads' ski jaunt, appearing to put his hand on another woman's waist as he dances.
And at one stage the woman believed to be Sophie performs the sexy dance move known as the Slut Drop.
One tourist, who said the Prince looked "the worse for wear," told how onlookers were astonished by the future king's antics.
The clubber said: "He was dancing so wildly that I did a double take when I first saw him and thought it must be a lookalike.
"But before long everyone realised they really were partying with Prince William.
"I decided I had to film it with my phone or no one would ever believe me.
"He was dancing with a very attractive blonde girl to hip hop and really going for it - it was proper dad dancing.
"I'm not sure whether it was the drink but he didn't seem to care how he looked and I never saw any security guys keeping an eye on him or his three mates.
"He started trying on hats starting with a skier's bobble hat then a cowboy hat while he danced with the blonde. It was a hilarious sight."
One clip shows balding Wills, dressed down in a pale blue shirt and jeans, waving his arms in the air as he tries to whip up the crowd in the brash Farinet Night Club on Sunday.
On Monday one female partygoer referred to William's dirty dancing by posting Instagram pictures of herself inside the club with the hashtag #slutdropwithaprince.
A slut drop is a dance move which involves squatting as quickly and as low as possible and immediately popping back up.
The highly embarrassing phone footage comes after William was heavily criticised for ducking out of a Commonwealth Day service to go on the trip to ski resort Verbier with his mates Guy Pelly, James Meade and Tom Van Straubenzee.
The Queen was supported by other senior royals at Westminster Abbey at Monday's service.
Wills was instead enjoying a boozy lunch on the slopes with his friends and topless model Sophie, 24, ex-Blackpool beautician Rosie Peate, 30, and Sophie's boyfriend Aaron Goodfellow - before going clubbing.
Adriana Domingo, 28, waitress at the La Vache restaurant said Wills was the "life and soul" as he downed rose wine and pizza with the girls.
His mates picked up the £200-plus bill for the lunch and invited staff to join them drinking Jagerbomb shots before heading off for their apres-ski party.
Adriana said: "The Prince was a great guy and wasn't at all snobby.
"I'm a friend of Sophie and know she's with Aaron, so I know all this stuff about her being involved with the William is total nonsense."
Sophie and Rosie work at the Farinet Hotel and its adjoining bar and night club in the swish resort and declined to comment about their Royal friend yesterday.
She added: "It's safe to assume Kate will be far from happy.
"She's left at home with the children while William is off on a bachelor blow-out.
"It's known she doesn't like it when he goes off on his own stag dos and such things.
"As a couple they're very careful of their image and what they project. This is definitely not the image that Kate wants to convey.
"And Guy Pelly's heavily pregnant wife Lizzie is apparently very very unhappy with the photos of them cavorting with these two blondes."
William returned home to wife Kate and their children on Monday night and was back on duty as a helicopter pilot for East Anglia Air Ambulance yesterday.
Royal expert But Katie Nicholl, author of Kate: The Future Queen, said he would have got a frosty reception at home.