A painting previously believed to be a copy of a work by Raphael looks likely to be the real thing.
The piece is a portrait of the Madonna and dates to between 1505 and 1510.
Historian Bendor Grosvenor discovered the piece while touring Haddo House in Scotland for an upcoming BBC TV show.
Grosvenor told the Guardian newspaper: "I thought, crikey, it looks like a Raphael…
"It was very dirty under old varnish, which goes yellow… Being an anorak, I go round houses like this with binoculars and torches. If I hadn't done that, I'd probably have walked past it."
It transpires the work had originally been bought as a Raphael but was later downgraded to a work painted in his style by another artist, Innocenzo da Imola.
However Grosvenor felt the quality of the work was too high to be a piece by da Imola.
Subsequent investigations have revealed tell-tale signs that the work is an original rather than a copy. The positioning of a finger has been changed, indicating that the design was altered during the drawing stage.
It also matches other portraits of the Madonna by Raphael.
The work was valued at £20 in 1899, when thought to be a copy. That's around £2,000 ($2,554) today. If it does turn out to be by Raphael, it could be worth as much as £20m ($25.5m).
Click here to check out all our art and photography memorabilia for sale.
Please sign up to our free newsletter to receive exciting news about art and photography auctions.