A fake Monet painting, which featured on the BBC's Antiques Roadshow, could fetch up to £15,000 at auction.
The painting goes under the hammer on Friday (Pic: JP Humbert Auctioneers)
Tom Keating's view of Santa Maria della Salute and Grande Canal, Venice, is expected to attract a lot at the Northants sale on Friday.
Auctioneer Jonathon Humbert said the unsigned work was a very close likeness to the original.
The painting was presented to the Antique's Roadshow in the 1990s by a viewer who was unsure of its worth.
"It was brought on by someone who knew it was a fake, and was told it was worth about £15,000," Mr Humbert said.
"Had it been signed Monet, that would have caused us a problem - but Tom Keating in the 70s and 80s specialised in plagiarising all the great masters' work.
"He never actually signed them by either his name or the name of the artist he was taking off, so technically we are allowed to sell it - he was not trying to pass it off as by the original artist."
Keating, who died aged 67 in 1984, hit the headlines in 1979 when he admitted nine paintings said to be drawings by Samuel Palmer were, in fact, his copies. He maintained his motives were not for profit, but to expose the fallibility of art experts.
His notoriety led to his own work becoming popular and in 1983 Christie's auctioneers sold 135 of Keating's paintings for £72,000.
The fake Monet has attracted a lot of interest worldwide ahead of its auction in Towcester, the auctioneers said.
"To the untrained eye it looks exactly like it - but it's 99% the quality of a Monet for 1% of the price," Mr Humbert added.