Duke of Westminster Gerald Cavendish died of heart attack

Gerald Cavendish Grosvenor was estimated to be the third richest person in the UK

The billionaire landowner and philanthropist the Duke of Westminster died of a heart attack, Preston coroner's office has confirmed.

Gerald Cavendish Grosvenor died aged 64 at the Royal Preston Hospital in Lancashire on Tuesday after suddenly becoming ill on his Abbeystead Estate.

A spokeswoman for the coroner said there would be no inquest because the cause of death was natural.

The duke was said to be the third richest person in the UK.

He became the sixth Duke of Westminster in 1979 and his fortune was estimated at $10.8bn (£8.3bn), according to Forbes magazine, making him the 68th richest person in the world.

A friend of the Royal Family, the Territorial Army major general's only son, Hugh Grosvenor, 25, is to inherit his title.

On the Grosvenor Estate website, a message posted read: "He was a passionate country man, committed soldier, an excellent shot, a true entrepreneur and, importantly, he went out of his way to be courteous and humorous with all people, regardless of status or wealth."

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Lancashire Police said the duke had been walking in the Trough of Bowland when he was taken ill and later airlifted to hospital, where he died.

The duke owned 190 acres in Belgravia, adjacent to Buckingham Palace and one of London's most expensive areas, as well as thousands of acres in Scotland and Spain.

He supported a number of charities and good causes, including making a £500,000 donation to farmers during the 2001 foot-and-mouth outbreak.

Due to the rule of male primogeniture - which blocks women receiving hereditary peerages - the dukedom is passed to his third-born child, Hugh Grosvenor, instead of his older daughters, Lady Tamara and Lady Edwina.