LONDON - A drawing by Andrea del Sarto has resurfaced and will go on sale July 5, at Christie's in London. Del Sarto is considered to be the last great Florentine artist of the High Renaissance, but was overshadowed by his contemporaries, Michaelangelo, Raphael and Leonardo da Vinci. Head of St Joseph, a study for a picture now in the Pitti Palace in Florence, is a work of exceptional quality and is expected to sell for 1.5 million pounds.

The drawing is one of the last by del Sarto to remain in private hands and is the most significant to be offered to the market for 70 years. While a photograph from the 1920s had alerted scholars to the existence of this work, its whereabouts has been a mystery. The work has reappeared after more than 50 years in a private Swiss collection. Inspection has revealed a drawing on the reverse of the sheet that is previously unpublished and entirely unknown to scholars.

The first known owner of the drawing was the artist and biographer Giorgio Vasari who was one of del Sarto's pupils. Vasari was the first 'modern' collector of drawings, and is most famous for his Lives of the Artists, perhaps the earliest work of modern art history and criticism. He assembled a collection of drawings by notable artists from the 14th century to his own time and arranged them in albums with distinctive decorative frames drawn around the mounts, as can be seen in the Head of Saint Joseph.