Competitive bids are expected at Sotheby's London on July 9, as the auction house offers the only drawing by Sandro Botticelli in private hands.

The masterwork for which this study was created is now part of the Faringdon Collection

Selling as part of the Old Master and British Paintings auction, the drawing is one of nine renaissance and baroque masterworks from the estate of art connoisseur Barbara Piasecka Johnson. It is estimated to sell for £1m-1.5m. ($1.6m-2.5m).

Study for a Seated St Joseph is the only work on paper from Botticelli (1445-1510) to have appeared at auction since the 19th century, with most now housed in museums and institutions.

It is a study for the figure of St Joseph in Botticelli's masterwork The Holy Family with the infant St. John the Baptist, which is housed in the Faringdon Collection at Buscot Park, UK.

Cavarozzi is considered one of the most talented followers of Caravaggio

The top estimate in the sale goes to Sacrifice of Isaac by Bartolomeo Cavarozzi (1587-1625), who is celebrated as one of the most talented followers of Caravaggio.

Estimated at up to £5m ($8.4m), the piece was painted in 1617, shortly after Cavarozzi had moved to Madrid having trained in Rome.

Also set to excite bidders are two major drapery studies created in what Sotheby's describes as one of the most important workshops of the renaissance, the bottega of Andrea del Verrochio (1435-1488).

While they cannot be attributed directly to him, Leonardo da Vinci developed the technique of drawing drapery while studying under Verrochio. The two drawings were originally part of a "hugely important" group of 16 drapery studies, and are the only two available to collectors.

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