A statuette of the Virgin and Child that has lain dormant in a private collection since the mid-20th century has been consigned to Sotheby's European Sculpture and Works of Art auction in London on December 4.
The piece has been protected by a community of nuns for much of its history, and has also passed through the hands of two noble English families. It is valued at £800,000-1.2m ($1.3m-1.9m).
Sotheby's Erik Bijzet commented: "When I first laid my eyes on it and held it, I knew it was the start of what was to become one of the most rewarding challenges in my career.
"Uncovering documents, many of them centuries old, revealed tantalising new discoveries until the full story finally emerged. The statuette is wondrously detailed, as is its history."
Dating to 1250-1260, the statuette was likely made in northern France. It is said that the statuette mysteriously appeared on the doorstep of the Bridgettine nuns residing in England's Syon monastery in the early 15th century, concealing a note that read, "AVE MARIS STELLA".
The monastery suffered heavily during the Reformation, and the nuns fled to the Netherlands in 1559, where they were persecuted by the Calvanists.
They eventually settled in Lisbon in 1594, having received strong support from the king.
However, having endured 200 years in Lisbon, including the destruction of their monastery by fire and an earthquake, the nuns returned to England in 1809. By 1836, only two nuns remained, and they soon traded their belongings with the 16th Earl of Shrewsbury, John Talbot, for shelter and a pension of £30 a year.
The statuette was then passed to Talbot's son, and later given to the Duchess of Norfolk, Charlotte Sophia Fitzalan Howard, the only Catholic in the family.
It was presented to the duchess' son-in-law James Hope-Scott, who loaned it to the Victoria and Albert Museum before it disappeared.
It was then thought lost until it was bought from a well-known art dealer by an ancestor of the current owner in 1949, and has remained in their collection since.
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