The artwork, one of four portraits of the Austrian composer painted during his lifetime and still part of a private collection, was painted in 1770. It has been attributed to Italian painter Giambettino Cignaroli.

The oil-on-canvas portrait depicts a 13-year-old Mozart in a white wig and a red frock coat playing the harpsichord, with the musical score just visible at the edge of the frame.

“What’s very interesting about that portrait is the musical score. It’s actually only known from that portrait, so some musicologists have said it could be the work of Mozart himself,” said Astrid Centner-d’Oultremont, head of the Old Masters department at the British auction house’s Paris branch.

At the time of the painting, Mozart was travelling in Italy as he continued his artistic education, giving concerts all around the country.

The portrait was ordered by Venetian receiver-general Pietro Lugiati some days after an organ concert Mozart performed in Verona in January 1770.

Mozart was born in 1756 in Salzburg in Austria, and died in 1791. (Reporting by Michaela Cabrera; Writing by GV De Clercq; Editing by Hugh Lawson)