The Duke of Devonshire has died at his Derbyshire home, Chatsworth House, at the age of 84.
The Duke supported fox hunting
A spokesman at Chatsworth said the duke died on Monday night with his wife the Duchess at his side.
In accordance with the duke's wishes, Chatsworth House - one of the country's most popular stately homes - remains open to the public.
The duke, Andrew Cavendish, was the Peak District's largest landowner.
The owner of the 12,000-acre Chatsworth estate was a well-known supporter of fox hunting.
He served in the Coldstream Guards during the war, and was mayor of Buxton from 1952 to 1954.
The 11th Duke of Devonshire was a minister in the Conservative government 1960-64, led by his uncle, Harold Macmillan.
The duke married the Hon Deborah Mitford, daughter of Lord and Lady Redesdale, in 1941 and they had three children.
He also leaves eight grandchildren and four great-grandchildren
In 1998, the duke and duchess became the longest serving holders of the Devonshire dukedom.
And the couple were long-standing friends of the Queen, who Buckingham Palace said was "saddened" by the news.
Prince Charles and Camilla Parker Bowles were regular visitors to Chatsworth House and shared a love of countryside pursuits with the Devonshires.
The Prince of Wales was "deeply upset" by the death of the duke, with whom he was "great friends", Clarence House said.
The heir to the throne said in a statement: "I am deeply upset by the death of the Duke of Devonshire, for whom I had a great personal affection and admiration."
Second Division Chesterfield FC will hold a minute's silence before their last
game of the season this Saturday at home to Luton Town as a mark of respect to
the duke, who was the club's president.
Club chairman Barrie Hubbard said: "His Grace the Duke of Devonshire was club president for nearly 50 years and has always kept a healthy interest in the fortunes of the club.
"He was with us when the club received the freedom of the borough of
Chesterfield for the historic FA Cup run in 1997 and then was especially helpful
when the club was in serious financial difficulties in recent years."
Condolences from everyone at Chesterfield FC have been sent to the Duchess of
Devonshire on her sad loss, the club said.