Ida Maud Fussell, who died last October at the age of 88, had married Percy Fussell, a brewery chief, after acting as his housekeeper for 21 years.
She died at her home in the village of Rode, Somerset, without having any children and left the entire pounds 9,998,787 estate to her nephew Richard Oatley.
Mr Oatley, a bachelor in his forties, owns a smallholding in Rode and makes his livelihood fattening calves for sale at market, but is said to have little interest in the fortune.
The Fussell empire began in 1744 when they founded toolmaking and iron smelting businesses in Frome, Mells and Rode. Branches of the family later diversified into garden furniture and, shortly before the First World War, Percy Fussell set up a brewery with his brothers Henry and Reginald.
Relatives of the other brothers have seen little of the profits from the brewery - which was bought out by Bass in the 1960s - come their way. But Barbara Wheeler, Henry Fussell's daughter, said that the situation had been known and accepted for many years.
"It is one of those things. Although Ida's name was Fussell, she had only marital connections with the family and we saw her rarely," Mrs Wheeler said.Reuse content