Billionaire landowner the Duke of Westminster has died at the age of 64.
Gerald Cavendish Grosvenor died on Tuesday afternoon at the Royal Preston Hospital in Lancashire.
A spokeswoman for his estate said he had become ill suddenly on his Abbeystead Estate.
The Duke's fortune was estimated at £9.3 billion pounds by the latest edition of the Sunday Times Rich list this April, making him the sixth wealthiest man on the list.
Forbes placed him as the 68th richest man in the world.
He owned swathes of land across the UK and beyond including large areas in west London's Belgravia and Mayfair.
One of his four children, Hugh Grosvenor, is Prince George's youngest godfather.
A spokesman said his family wanted privacy as they mourn his loss.
A Clarence House spokeswoman said the Prince of Wales and Duchess of Cornwall are "deeply shocked and greatly saddened" by the sudden death of their friend the Duke of Westminster.