William Parente inherited 62,000 acres of the East Midlands, including the 15,000 acre Welbeck Abbey estate in Nottinghamshire, when his aunt, Lady Anne Cavendish Bentinck died in 2008.
The inheritance also included another 45,000 acres in Scotland, Bothal Castle in Northumberland, 30 prime acres of Central London around Harley Street and a hugely valuable collection of significant artworks.
The Welbeck Estates Company had net assets exceeding £85 million in 2010-11.
William Parente, aged 61, the only grandchild of the 7th Duke of Portland, is involved in the Welbeck Project, a scheme to transform 33 listed and architecturally significant 18th and 19th century buildings into a 21st century business community.
The project, supported by the charitable Harley Foundation, is bringing together rural industries, the arts, the creative industries and technology companies. Premises include a farm shop, an art gallery, a bake-house, a book exporter, a cooking school and a working dairy. The dairy produces the organic Stichelton cheese, using milk from a herd of Holstein Friesians on the estate.
The Welbeck Abbey estate was mentioned in the Domesday Book and can trace its roots back to 1120. It was used by the Ministry of Defence until 2005, after which it became the family home.
William Parente served as the High Sheriff of Nottinghamshire in 2003-2004. The main family business is Bolsover Properties which has assets of nearly £9 million. However it is the works of art which make up much of the family fortune, probably worth more than £100 million.