Gallery admits portrait isn't Bonnie Prince Charlie

• Picture: Complimentary

But now, in an embarrassing climbdown, the National Galleries of Scotland has admitted that the painting – purchased by them for 22,000 – is not of Charles Edward Stuart at all.

The portrait, by the French master Maurice-Quentin La Tour, has hung with pride in the Scottish National Portrait Gallery since it was bought in 1994.

A row has been rumbling on for two years over the work after London art dealer Bendor Grosvenor claimed it was not of Bonnie Prince Charlie, but his younger brother Henry.

Initially, the gallery stoutly defended its painting from attack, insisting it was definitely of the prince and citing Stuart portrait expert Dr Edward Corp of the University of Toulouse in its defence. He firmly rejected claims that it was the younger prince.

Now, however, Dr Corp has changed his mind.

The fact the sitter was wearing armour had seemed to point to Charles – Henry was a cardinal, and would not have been pictured in military garb. But Dr Corp has discovered that at the time the portrait was made, Henry was leading a naval expedition in support of his brother and had not yet been made a cardinal – so he could well have posed in armour.

The expert has also concluded that the painting is an almost exact likeness of another portrait of Henry. He said: "The weight of evidence – perhaps regrettably – supports Bendor Grosvenor's argument that the pastel in the Scottish National Portrait Gallery shows Prince Henry rather than Prince Charles.

The iconic portrait of Bonnie Prince Charlie by Maurince-Quentin La Tour

"Whether the portrait does or does not show Prince Charles really does matter. It is not merely the catalogue of the Scottish National Portrait Gallery which needs to be corrected.

"The impression which an entire nation has derived of this important historical figure should also be changed."

Dr Corp's change of heart was revealed in an edition of the British Art Journal this week.

Despite their earlier defence of the work, gallery officials now accept they were wrong – and that the painting is of Henry.

A spokesman for the National Galleries of Scotland said: "Dr Edward Corp, an authority on Jacobite imagery, has … defended the identification of the sitter in our pastel as Charles.

"However, in a recent article for the British Art Journal, Dr Corp re-considers this position.

"In the light of this development, we have reassessed our own position and, on balance, accept that it is more likely that our pastel depicts Prince Henry Benedict, and not his elder brother."

British Art Journal editor Robin Simon welcomed the gallery's about-turn.

He said: "There is no doubt at all. But it's rare that anything is so spectacularly wrong."

The 5ft-tall pastel of the man in armour was bought at auction by the gallery. It came to be seen as a classic image of the prince, and was used as the cover for an edition of Fitzroy Maclean's biography of him, as well as appearing as the face of Prince Charles in the Oxford Dictionary of Biography.

Charles, also known as the Young Pretender, was the elder son of the Old Pretender, James Edward Stuart, and the grandson of James II and VII. He fled into exile after his forces were defeated at Culloden.

Dead ringer: Charlie's brother sat for artist

THE detective work to determine who the portrait was of started after a painting called Portrait of a Cardinal was auctioned in London from the collection of St Mary's Roman Catholic College, Twickenham.

It was bought by London dealers Philip Mould. After cleaning it and comparing it with other pictures, it was identified as a lost portrait of Henry. Bendor Grosvenor, a director of the firm, became convinced it was a copy of the Scottish National Portrait Gallery's pastel. "It was a dead ringer. He compared the details of his portrait of a cardinal with this La Tour pastel. It was a brilliant thing to have done," said Robin Simon, editor of the British Art Journal.

"You can see how it happened. People got muddled over who sat for La Tour and missed the rather important point that Cardinal Henry had also sat for him."

Little brother went from riches to rags

PRINCE Charles Edward Stuart, also known as the Young Pretender, was the elder son of the "Old Pretender", James Edward Stuart, and the grandson of James II and VII. He fled into exile after his forces were defeated in battle at Culloden.

His brother, Prince Henry Benedict, was born five years after Charles in 1725. He was known as the Duke of York or Cardinal York until his brother's death in 1788, when he claimed the title of Henry IX.

Unlike Charles, Henry never attempted to seize the throne or challenge the Hanoverian rule of Britain.

He did, however, support his brother by trying to organise a naval expedition to support the '45 rebellion.

After the failure of the Jacobites in 1746, Henry embarked on a career in the upper echelons of the Catholic Church, being created a cardinal by his godfather, Pope Benedict XIV, in June 1747. This move, however, in addition to the seizure of his property by the French, led him into poverty.

The British minister in Venice arranged an annuity of 4,000 from King George III of Great Britain, which was portrayed as an act of charity.

Henry returned to Frascati, near Rome, in 1803, becoming the Dean of the College of Cardinals and hence Cardinal Bishop of Ostia and Velletri.

He died on 13 July, 1807, at the age of 82.