Biographer claims Prince William danced to Grease medley at wedding

Prince William performed a choreographed dance to a Grease medley at his wedding, according to a new royal biography.

A new book about Catherine, Princess of Wales has lifted the lid on their wedding night, revealing she and William danced to a Grease medley before exiting their reception.

"For the evening's finale, Prince William and Kate had a special surprise up their sleeves," Robert Jobson wrote in his new biography, Catherine, the Princess of Wales.

"They stood holding hands in the middle of the dance floor grinning, then suddenly the opening bars of the song You're the One That I Want from the musical Grease came booming out."

Jobson, who acts as Royal Editor of the London Evening Standard, went on to describe the pair's choreographed wedding dance.

"William and Catherine then began dancing around, pointing at each other, and mouthing the words with the style of the lead characters Danny and Sandy," he wrote.

"It brought the house down."

The book also claimed it was William's ex-girlfriend, Carly Massy-Birch, who first broke the news of his previously undeclared romance with Catherine, when all three were still university students.

During a party game of Never Have I Ever, which requires players to name something they have never done, Carly reportedly said, "Never have I ever dated two people in this room", forcing William to confess he was, in fact, dating Catherine.