The Duke of Marlborough died this morning, aged 88.
Blenheim Palace – where he held his principal seat – confirmed the news. His cause of death is not yet known.
"With great sadness, we announce that the 11th Duke of Marlborough passed away peacefully this morning," read a statement from the palace.
"Further announcements will be made in due course. As per his wishes, the Palace will be open as normal today."
The Duke – whose real name was John George Vanderbilt Henry Spencer-Churchill - was a generational cousin of Winston Churchill and distant relation of Diana, Princess of Wales.
He was married four times and has four children, his heir Lord Jamie, 58, Lord Edward, 40, Lady Alexandra, 37, and Lady Henrietta, 56.
The flag is flying half-mast at Blenheim Palace in Oxfordshire today. The Palace will close at 2pm tomorrow as a mark of respect.
David Cameron said that he was "greatly saddened" to learn of the Duke’s death calling him "a good man and a friend".
"His Grace will be deeply missed by all those he worked alongside at Blenheim and by the town of Woodstock where he played such a positive and active role in the community he loved," said Cameron, according to the Oxford Mail.
"My thoughts and prayers are with all his family and friends at this sad time."Reuse content