The 10 x 12in (25.5 x 30.5cm) secretaire, made out of papier-mâché and decorated with mother-of-pearl, was taken from a ground-floor gallery at the museum, where it had been since 1917, between 11.15am and 5pm on Sunday, November 11.
It is thought that the desk was used by Mary Anne Evans - who wrote under the name of George Eliot - when she lived at Griff House (1820-41), a spacious farmhouse on the road between Nuneaton and Coventry.
The museum believe it was specifically targeted and possibly stolen to order. They say: "To gain access to it, those responsible had to remove a display case. To add insult to injury, it is believed that the theft took place soon after thousands of members of the public had turned out to pay homage to fallen soldiers at the Nuneaton Remembrance Parade which took place only metres away from the scene of the crime."
Anyone with any information should call Crimestoppers on 0800 555111.