An uncatalogued LS Lowry painting has been rediscovered after 57 years in a private collection.
The painting could fetch £1m at auction in December
The work, A Fairground, was bought sometime around 1950 and has remained in the same family ever since.
It is believed to depict a fair in Beswick, in Manchester. The artist painted the fairground scene in 1938 but it was never catalogued or shown.
Experts only became aware of it when the family approached Sotheby's, who called it "an exciting re-discovery".
One of the few clues to the painting's history is a fragment of a stock label on the back from an old frame.
Sotheby's said the discovery, "signifies a new and momentous addition to the currently known body of work by the artist".
A Fairground is one of two Lowry works to be auctioned at Sotheby's in London on December 13, and is estimated to fetch £700,000 to £1m.
The other is The Football Match, which depicts a game taking place against a backdrop of chimney stacks and industrial buildings, also expected to fetch about £1m.
James Rawlin, head of 20th Century British art at the London auction house, said: "Both works display all of the qualities that make Lowry's painting so accessible and they also show him at his very finest."
This is thought to be especially important as the thirties, when Lowry painted the picture, is widely believed to be the decade when Lowry honed his individual style.
He said of the fairground painting: "This work is not mentioned in any books and has never been exhibited as far as anyone can ascertain. It is a genuine rediscovery.
"It has been in the hands of a British family all these years. They have always known what it was and have decided now is the time to sell it."
The record price for a Lowry painting is the £3.7m in June for Good Friday, Daisy Nook.