Gerald Cavendish Grosvenor, known as the Duke of Westminster, whose central London property holdings made him the U.K.’s wealthiest native-born person, has died. He was 64.

He died Tuesday afternoon at the Royal Preston Hospital in Lancashire after suddenly falling ill at his Abbeystead Estate in north England, according to the Press Association. No cause was given.

The duke inherited land his family has owned since 1677, including swathes of London’s Belgravia and Mayfair neighborhoods. His London-based real estate firm, Grosvenor Group, had assets under management of 13 billion pounds ($19 billion) in 2015. He and his family had a fortune of $12.3 billion, according to the Bloomberg Billionaires Index.

Grosvenor was born in 1951 and spent his childhood in the rural countryside in Northern Ireland before attending Harrow boarding school in London. After leaving, he joined the British Territorial Army -- which included a period of training at Royal Military Academy Sandhurst -- and traveled in Canada and New Zealand.

He eventually returned to Britain, working at a central London real estate agency to better understand the local property market. When his father, Robert, fell ill in the 1970s Grosvenor took over the family estate. He inherited the title of Duke of Westminster in 1979 from his father, who had received it after his older brother died 12 years earlier without leaving any male heirs.

As duke, he was chairman of the trustees of the Grosvenor Estate, the portfolio of properties and businesses that’s been in his family for centuries, originating with the 500 acres of London land Sir Thomas Grosvenor came into when he married heiress Mary Davies in 1677. Today, the family’s assets have grown to include prime London commercial property, rural estates in England, Scotland, Wales and Spain and an international property development, investment and fund management business, Grosvenor Group.

He married Natalia Ayesha Phillips, a descendant of the Russian author Alexander Pushkin, in 1978. They had three daughters, Tamara, Edwina and Viola, and a son, Hugh.