The portrait by Maurice Quentin de la Tour has become an iconic image
One of the best known images of Bonnie Prince Charlie may in fact portray his younger brother, according to research by an art expert.
The Scottish National Portrait Gallery's pastel portrait by Maurice Quentin de la Tour has become an iconic image of the prince.
But research by London-based art dealer Bendor Grosvenor suggests it may have been mistakenly identified.
The Scottish National Portait Gallery maintains the image is Charles.
It bought the portrait in 1994 for £22,000.
Prince Charles Edward Stuart, or Bonnie Prince Charlie as he became known, was the grandson of James VII of Scotland (James II of England), who was deposed in 1688.
The key to the unlocking the mystery came in February this year when a painting catalogued simply as "Portrait of a Cardinal" came up for auction. It was bought by London art dealers Philip Mould.
After careful research by Mr Grosvenor, one of the company's directors, it was identified as a lost portrait of Prince Charlie's younger brother, Henry Stuart, who is best known as Cardinal York.
But the trail led further, as Mr Grosvenor told the BBC Scotland news website.
This portrait bought at an auction in London this year was the key
"I was reminded that I had often thought the portrait in the Scottish National Portrait Gallery looked a little bit strange," he said.
"Charles had a prominent dimple and his face was much more angular than Henry's."
Mr Grosvenor compared the different images using computer technology and came to the conclusion that the picture in Edinburgh is Henry rather than Charlie.
He also argued that the painting bought this year in London is an updated copy of it simply showing different (clerical) clothing.
Mr Grosvenor said earlier art experts may have been misled by the fact that the subject of the portrait is in armour - not the generally accepted clothing of a cardinal.
Yet Henry was briefly a soldier and, according to Mr Grosvenor, he "loved dressing up". He also sat for a portrait by de la Tour.
All of this, he said, actually makes the Edinburgh-portrait "even more interesting".
That view has been echoed by Robin Simon, editor of the British Art Journal, which published the research. He said he had "no doubts" about the research.
Of the portrait he added: "It is just a wonderful piece anyway. It's superb."
The Scottish National Portrait Gallery acknowledged that there had always been some "scholarly debate" about the subject of the painting.
Both men looked similar in their younger years and both were painted by de la Tour.
The gallery's director, James Holloway, said: "The reason we maintain that our portrait does, in fact, represent Prince Charles is because of its very close similarity to the engraving by Michel Aubert published contemporaneously with an inscription identifying it as Prince Charles.
"To date there has been no convincing evidence that contradicts this identification."
But Mr Grosvenor, who describes himself as "a bit of a Jacobite-anorak", said the historical detective work had been "highly exciting" and he felt as though he had "hit the jackpot."