Art experts claim a previously unknown drawing by Michelangelo which lay unrecognised for more than 250 years could fetch up to £8m at auction.
The pen-and-brown-ink study of a Mourning Woman was found in a scrapbook during a routine inventory at Castle Howard, Yorkshire, eight years ago.
Since then, various experts around the world have studied the drawing and have confirmed it as a genuine early Michelangelo, dated around 1500.
Now the work - one of only four in the world still in private hands - is to go up for auction at Sotheby's in London on July 11, when it is expected to sell for between £6m and £8m.
"There have been only three major Michelangelo drawings on the market in the last quarter century," said Director of Old Master Drawings at Sotheby's, Gregory Rubinstein.
"The last one that was sold was sold for a record price. This drawing has to be comparable in terms of value and it is possible it too will go for a record."
The early drawing was discovered by Sotheby's expert, Julien Stock, while carrying out a routine inventory at Castle Howard.
While looking through a 19th century scrapbook in the Library at Castle Howard, Mr Stock recognised the work immediately as part of a small group of large-scale figure studies by the Italian Renaissance artist, sculptor and architect.
The study, which shows a three-quarter length view of a woman from the side and with her face obscured, is thought to have languished virtually unseen for more than 250 years.
Although there is no record of when the drawing came to Castle Howard, experts think the drawing was bought by the fourth Earl of Carlisle, Henry Howard, at auction in 1747.