The former Conservative MP died at his Bowhill House home in the Scottish Borders after being treated for a short illness at Borders General Hospital.

The duke, who used a wheelchair after a riding accident in the early 70s, was a strong supporter of country pursuits.

He was believed to be Britain’s biggest private landowner, owning 270,000 acres, mostly in the Borders. The Sunday Times Rich List estimated his wealth at £85m.