Rare Mozart portrait goes under hammer in London

Mozart's present is referred to several times in a series of letters sent to Maria Anna Thekla Mozart, with whom he developed an intimate but fleeting relationship.

The rare 4-centimetre (1.6-inch) high portrait was made by an anonymous artist in 1777, when Mozart was 21, and Maria Anna was 19.

"One of only two authentic paintings of Mozart remaining in private hands and one of only a dozen or so authentic paintings and drawings of the composer, this object's significance is virtually unparalleled," said Stephen Roe, Sotheby's Worldwide Head of Books & Manuscripts.

"Mozart's features come as a revelation when viewed in the flesh; the detail in the face is remarkable, formed by the tiniest dots of gouache applied with the utmost precision and delicacy, and a marvellous luminosity pervades the entire image."

In the piece -- watercolour and gouache on ivory -- Mozart wears a red coat and has his blond hair powdered and tied with a large black bow.

Maria Anna was the daughter of his uncle Franz Alois Mozart and the two met as adults during a two-week stay in Augsburg in 1777 and enjoyed a close and playful friendship.

As well as swapping portraits, the pair exchanged nine letters, which revealed a scatological and often infantile humour.

But the relationship cooled off when Mozart fell deeply in love with Aloysia Weber in Mannheim.