A picture of a speeding car produced by an artist known for his Falmouth and Helford River landscapes is expected to reach £60,000 at auction.
The artwork by Cyril Power was originally thought to be worth about £20, but turned out to be a classic print.
The American owner has left the work hanging on the wall of his garage for 25 years, unaware of its significance.
But Tony Wilson, head of automobilia at Bonhams spotted it at the Automobilia Exhibition in California spotted it.
It was then identified as Speed Trial, inspired by Malcolm Campbell's Bluebird which broke the landspeed record in 1931 after hitting 246mph.
Rupert Worrall, head of prints at Bonhams, said: "This is a particularly nice Power that will doubtless attract a lot of interest from people who collect his work and which grows in popularity each year."
Cyril Edward Power (1872 – 1951) was an English artist who helped co-found The Grosvenor School Of Modern Art in London in 1925.
In the last year of his life he completed 89 paintings, mainly landscapes of the surrounding areas, often the Helford River and the Falmouth area.
He died in London aged 78.