The search is on for an online art lover who paid £3,000 for a painting on eBay eight years ago that has since been revealed as an impressionist masterpiece worth around £250,000.
Experts on the BBC antiques show Fake Or Fortune made the discovery when they valued a painting owned by writer Keith Tutt.
He had bought the canvas, now established as the work of French painter Edouard Vuillard, for a knock-down price at an auction.
It had previously been owned by art dealer Robert Warren who revealed it was one of a pair and said he had sold the other, depicting a couple eating oysters and drinking champagne, on eBay but could not remember who bought it.
The show's co-presenter Philip Mould said: "This is a wonderful example of what can happen in this programme. In the course of making the programme we threw everything into the pot in terms of forensics, science, historical (provenance) research, and even established that it been painted in distemper made from boiling hot animal glue.
"An amazing add-on has been to prove that now there is out there, possibly hanging above someone's fireplace, this further missing treasure. And they almost certainly don't know it."
Fiona Bruce, who co-hosts the show, said: "You can't miss this painting, it's very large at four feet high and an unusual oval shape. Whoever bought it off eBay has bagged themselves the bargain of the century.
"We've done all the forensic and investigative work to prove it's genuine, now we just need to find the owner and tell them the good news. Someone, somewhere in the world is sitting on a fortune."