The duke, who died in September, managed to convince the Rich List -- which monitors the country's super-rich -- that he was worth only about 85 million pounds ($170 million), The Scotsman reported. But his will shows he had a far larger net worth.
His assets include 280,000 acres of land and Drumlanrig Castle, Bowhill House and Dalkeith Palace in Scotland and Boughton House in Northhamptonshire.
Most of the estate -- which includes paintings by Rembrandt, Gainsborough and Holbein as well as the recently recovered Madonna and the Yardwinder by Leonardo da Vinci -- goes to the duke's oldest son, Richard, now the 10th duke. The dowager duchess gets $400,000 and a car, either a Ford Focus or an Audi.
The duke was born Walter Francis John Montagu-Douglas-Scott. He served in the Navy during World War II, attended Oxford after the war and spent 13 years as a Conservative member of Parliament.