The 5ft 11in x 4ft 8in (1.8m x 1.38m) painting of the Old Pretender as a boy, when he was exiled to the French court, is one of three portraits documenting the childhood of the Stuart heir painted by Nicolas de Largillière (1656-1746). It carries an estimate of €120,000-150,000 (£135,000-168,000).
One example is in the National Gallery of Scotland, depicting him as a baby, and another, of him as a young boy, is in the National Portrait Gallery in London.
This third portrait, as a small child, was only recently discovered in the possession of the descendant of a Roman collector who had purchased it sometime after 1870. It shows the young prince, wearing a red dress (traditional for boys), a plumed hat and a blue sash bearing the Order of The Garter.
The image of the son of the deposed James II of England was previously only known through an engraving by Gérard Edelinck that was distributed among the Jacobites at home and abroad.
Portraiture helped maintain and encourage Jacobite support in England after his father was deposed in 1688 in favour of the Protestant William of Orange.
As the only son of James II and Mary of Modena, he became the focus of Jacobite resistance and mounted several unsuccessful campaigns to reclaim the throne in 1706, 1708 and in 1715.
He married Polish princess Maria Clementina Sobieska in 1719 and remained in exile, spending his later years in Rome.
The elder of his two sons was Prince Charles Edward Stuart, who came to be known as ‘The Young Pretender’.