The only life portrait of Prince William in existence has gone on display at a gallery in London.
But the portrait, by artist John Wonnacott, has already been sold to a mystery buyer who reserved the painting at the £100,000 asking price.
The oil on canvas was painted in preparation for a group picture of the Royal family to celebrate the late Queen Mother's 100th birthday.
It shows a 17-year-old Prince William when he was studying at Eton.
It went on public display for the first time on Wednesday at Agnew's gallery in Mayfair, London, alongside Mr Wonnacott's other preliminary works.
Gallery director Christopher Kingzett said: "A lot of people have been round to look at it.
"It actually went on reserve on Monday even though it only went on sale today."
Mr Wonnacott sketched the Prince in his housemaster's study at Eton.
"He kept wearing fancy waistcoats. He used to turn up in some real horrors which I asked him to take off," Wonnacott said.
"I'm the one person who has painted him. I suppose it was rather a special thing.
"Every girl in the country is jealous of me."
Three portraits also went on sale - two of the Queen Mother and one of the family group featuring the Queen, the Queen Mother, the Duke of Edinburgh, the Prince of Wales and Princes William and Harry.
They have also been put on reserve by the same buyer at £100,000 each.