In 2009 Gergely Barki, a researcher at Hungary's National Gallery, noticed "Sleeping Lady with Black Vase" by Robert Bereny (1888-1953) in the 1999 kids' movie about a mouse as he watched TV with his daughter Lola.



"I couldn't believe my eyes when I saw Bereny's long-lost masterpiece on the wall behind Hugh Laurie, I nearly dropped Lola from my lap," Barki, 43, told AFP on Thursday.



"A researcher can never take his eyes off the job, even when watching Christmas movies at home," he said.



The painting disappeared in the 1920s but Barki recognised it immediately even though he had only seen a faded black-and-white photo dating from a 1928 exhibition archived in the National Gallery.



Barki sent a flurry of emails to staff at the film's makers Sony Pictures and Columbia Pictures, receiving a reply from a former Sony employee, a set designer -- two years later.



"She said the picture was hanging on her wall," Barki told AFP.



"She had snapped it up for next-to-nothing in an antiques shop in Pasadena, California, thinking its avant-garde elegance was perfect for Stuart Little's living room."



After leaving Sony the set-designer sold the painting to a private collector who has now brought the picture to Budapest for auction.



Bereny, the leader of a pre-World War I avant-garde movement called the "Group of Eights", fled to Berlin in 1920 after designing recruitment posters for Hungary's short-lived communist revolution in 1919.



In the German capital, he had a romance with actress Marlene Dietrich, and, according to Barki, a rumoured fling with Anastasia, the mysterious daughter of Russia's last tsar Nicholas II.



Bereny's painting goes under the hammer December 13 with a starting price of around 110,000 euros ($137,350), staff at the Virag Judit auction house told AFP.



According to Barki, the buyer at the 1928 exhibition, possibly Jewish, probably left Hungary in the run-up to, or during, World War II.



"After the wars, revolutions, and tumult of the 20th century many Hungarian masterpieces are lost, scattered around the world," he said.