The 10th Duke of Roxburghe has died at the age of 64 following a lengthy battle with cancer, his family has announced.
Guy Innes Ker died peacefully at his ancestral home, Floors Castle, near Kelso, in the Scottish Borders.
He is survived by Virginia, the Duchess of Roxburghe, five children and five grandchildren.
The duke's eldest son, Charles, the Marquis of Bowmont, will succeed his father as the 11th Duke of Roxburghe.
His family said in a statement that he had fought his illness "with great courage and determination".
The statement added: "He was a wonderful and loving husband to Virge and devoted father to Rosie, Charlie, Ted, Bella and George and it is a desperate loss to us all.
"His family meant so much to him and he was always there to offer love, guidance and support.
"He really was a Corinthian figure who was a great sportsman, a passionate fisherman who made a huge contribution to fisheries management on the River Tweed and a successful businessman who modernised and turned Roxburghe Estates into the successful business it is today.
"He took particular pride in seeing the work he and Virge had undertaken to establish Floors Castle and Gardens as one of the premier visitor attractions in Scotland."
The duke was also a successful racehorse breeder.
His stud at Floors produced Attraction - the first horse to win the Irish-Anglo Guineas "double" in 2004.
The duke was educated at Eton College and Magdalene College, Cambridge, where he studied Land Economy.
He did his military training at the Royal Military Academy, Sandhurst, before becoming a lieutenant in the Blues and Royals in 1974.
He succeeded his father as the 10th Duke of Roxburghe the same year.
David Johnstone, chairman of landowners' group Scottish Land and Estates, described him as a "driving force in the modernisation of land ownership in Scotland".
"He was passionate about all aspects of the rural sector and was determined to make Roxburghe Estates a shining example of a modern estate business," he said.
"He made many friends during his remarkable life and will be missed greatly."