£3m masterpiece found in Swansea Museum storeroom
A 17th Century Flemish masterpiece worth about £3m has been discovered in Swansea Museum's storeroom.
The "important and beautiful" painting by artist Jacob Jordaens - a pupil of Peter Paul Rubens - was previously unknown to art historians.
The auction record for a work by Jordaens is £3.6m ($4.7m).
A local restorer had repainted the piece to give the horses pink manes and change the colour of the sky.
The painting was identified by art historian Bendor Grosvenor, for the new BBC Four series, Britain's Lost Masterpieces.
The piece is a rare preparatory oil study for one of Jordaens' best known works, Atalanta & Meleager, which hangs in the Prado Museum in Madrid.
Ben van Beneden, director of the Rubenshuis Museum in Antwerp, said: "It's a great find. I have absolutely no doubt whatsoever that we're looking at a quintessential painting by Jordaens."
A vital clue came with the discovery of a series of merchant's marks on the back of the painting.
These - a combination of the letter A and the coat of arms of the city of Antwerp, Jordaens' home town, proved the panel must have been made between 1619 and 1621.
Dr Grosvenor said: "At first glance, this painting looked to be a non-starter. But despite all the over-paint, there were glimpses of a great painting fighting to come out.
"We were able to reveal a picture that was not only important and beautiful, but one which helps us to re-write the story of one of my favourite artists, Jacob Jordaens."
The painting is thought to have belonged to Swansea Museum for nearly 150 years and had been catalogued as a work by an unknown 18th Century artist.
It is currently in London but will go on display in Swansea from Thursday.