Vincent van Gogh’s Peasant Woman in front of a Farmhouse was bought in the 1960s by an Italian resident in north London from a junk shop for £45.
Luigi Grosso spotted the painting was signed “Vincent” and while the shop owner assumed it was by an artist with that surname, the buyer suspected that it might be the real thing.
The painting has been authenticated by the Van Gogh Museum in Amsterdam, which dates it to July 1885, when the artist was living with his parents in the Brabant village of Nuenen.
It was x-rayed and underneath the landscape was an earlier composition of a man ploughing with oxen, which was related to a known Van Gogh painting of August 1884. At this time Van Gogh often reused old canvases to save money.
It is now set to be sold by its American owner through the London-based Simon Dickinson gallery, which will be taking it to the Tefaf fair in Maastricht between March 7 and 15.
Although the price at Maastricht is not being disclosed, it is understood to be around €12m-€15m.
It was traced back to Billington Farm in Staffordshire by Martin Bailey, where it was sold in 1967 by Uttoxeter-based auctioneer Bagshaws, which deals with cows and sheep along with occasional consignments of second-hand farm equipment.
Unrecognised as a Van Gogh, the landscape picture went for £4.
Mr Bailey, a Van Gogh specialist and writer for The Art Newspaper, has traced the history of the artwork of ahead of the latest auction.
Mr Bailey identified the 1967 seller as Charles Holme, whose father had acquired the painting, and spoke with Charles’ children.
The original owner was John Holme, who lived in Billington and supplied corn and straw in the area.
His grandchildren told Mr Bailey that in 1929 Mr Holme had accepted the painting in lieu of a debt over farm supplies.
The unnamed debtor who handed over the Van Gogh had lived in Newport Road, which runs between Billington and the centre of Stafford.
When Mr Holme's son Charles retired in 1968, Bagshaws held an auction at Billington Farm.
It was then that the painting of the cottage was sold - and through an unknown route it ended up a few months later in the Belsize Park junk shop in London.
In 1970 Mr Grosso consigned the painting to Sotheby’s Parke Bernet, which sold it for $110,000 at auction in New York to Hollywood film producer Joseph Levine.
Then in 1983 Levine sold the painting and it returned to Sotheby’s, New York, selling for $390,000.
It was sold to the current unnamed American owner for $1.7m in 2001.
Mr Bailey is now appealing for anyone in Staffordshire who may have information about its past to come forwards.
Mr Bailey said: "It would be wonderful if any readers have any idea about who the original owner of the Van Gogh might have been in the 1920s.
"All we know is that they are thought to have lived in Newport Road, on the western outskirts of Stafford, in Rowley Park."
For more information, or to get in touch with Martin Bailey, visit theartnewspaper.com/blog/the-astonishing-tale-of-the-eur15-000-000-van-gogh-which-was-sold-in-a-farmyard-auction-in-england-for-just-gbp4?