Reported by ABC News' Bruno Roeber:

LONDON - It is the stuff of dreams: Find a gem, an undiscovered masterpiece, buy it for a song and make a fortune.

This time the dream came true for Keith Tutt, at least according to the BBC's "Fake or Fortune," a show that sets out to establish whether a piece of art is a masterpiece or a fake.

"After many months of doing exhaustive forensic work - X-raying the painting, putting ultraviolet light on it, taking microscopic samples of paint from it and following the paper trail of this almost back, not quite but almost back to the moment it left the brush - we managed to establish it was genuine," "Fake or Fortune's" presenter Fiona Bruce told BBC Radio Monday morning.

"Fake or Fortune" determined that the painting it was scrutinizing was by the French Impressionist painter Édouard Vuillard, and worth about $410,000.

Keith Tutt, a lifelong Vuillard fan, saw the painting for sale at a local auction and was convinced it was a genuine Vuillard. It was always thought to be by Édouard Vuillard but did not appear on the historical lists and was never a proven example of his work. Despite the lack of proof, Tutt gambled his life savings on buying the picture. It paid off big time.

But this is not the end of the story.

This painting was sold by art dealer Robert Warren, but it was not the first Vuillard he had sold - the painting was one of a pair. The other was sold on ebay in 2005 for £3000, or $4,930 at today's exchange rate. Yes, you read that right: A picture worth $410,000 was sold for less than $5,000 on ebay eight years ago. That's an an 83-fold profit for the unknown buyer.

Sadly, Warren knew he had something good, and he spent years trying to prove the authenticity of the painting but could not get the evidence he needed to sell the painting at its correct value. Eventually, he decided to put the painting up for auction, where it was purchased by its present owner, Keith Tutt.

The hunt is no longer on for the artist but for the buyer who purchased it on eBay in 2005. Warren said he sold the painting so long ago that he could no longer identify the buyer, who might not know how valuable the painting is.

"Whoever bought this painting thinking it looks nice, they have a jolly good eye," said "Fake or Fortune's" Bruce.

But the painting would be hard to mistake: It is oval, 4 feet tall and colorfully portrays a man and a woman in a restaurant eating oysters, likely in France.

If that reminds anyone of a painting bought almost a decade ago, the first round of drinks is on you.