In pictures: Tributes to Duke of Westminster who dies aged 64

Gerald Cavendish Grosvenor, whose family seat is at Eaton Hall in Eccleston, near Chester, died on Tuesday afternoon, having suddenly become ill.

He had been transferred from his Abbeystead Estate to the Royal Preston Hospital in Lancashire.

The Prince of Wales and Duchess of Cornwall are "deeply shocked and greatly saddened" by the sudden death, a Clarence House spokeswoman said.

The Queen and Duke of Edinburgh will send a message of condolence to the Grosvenor family.

Professor Tim Wheeler, vice-chancellor and principal at the University of Chester, said: "The University is saddened to hear of the death of his Grace, Gerald Cavendish Grosvenor, 6th Duke of Westminster and the University’s Chancellor. 

"The Duke was installed as Foundation Chancellor in 2005 at a special service at Chester Cathedral. He was a tireless supporter of the University and used his influence to further the University’s interests at every opportunity. 

"He represented the University on many ceremonial occasions. 

"He was delighted to open the Westminster Building and Grosvenor House, reflecting his close association with the University. The University has lost a dear friend, enthusiastic backer and loyal champion.

"Our thoughts and prayers are with his family."

One of the Duke's four children, his only son Hugh, is Prince George's youngest godfather, while his wife Natalia is godmother to the Duke of Cambridge.

The landowner was said to be worth around 10.8 billion dollars (£8.3 billion), according to Forbes, making him the 68th richest billionaire in the world, and third in the UK.

He 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.

The Grosvenor family's spokeswoman said on Tuesday: "It is with the greatest sadness that we can confirm that the Duke of Westminster, Gerald Cavendish Grosvenor (64) died this afternoon at Royal Preston Hospital. He was taken there from the Abbeystead Estate in Lancashire where he had suddenly been taken ill.

"His family are all aware and they ask for privacy and understanding at this very difficult time.

"No further comment will be made for the time being but further information will follow in due course."

A Buckingham Palace spokeswoman said: "I can confirm that Her Majesty the Queen is aware of the news about the Duke of Westminster. A private message of condolence is being sent by the Queen and the Duke of Edinburgh."

The Duke suffered a nervous breakdown and depression in 1998, saying the pressures of business and the great number of public appearances he was making overcame him.

In his early 20s, on becoming trustee of the estate, he had been forced to abandon his dream of a career in the Armed Forces, satisfying his love of all things military by serving in the Territorial Army.

He became the sixth Duke of Westminster at 27, and later credited himself with using his vast wealth responsibly.

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

Of his wealth he once said: "Given the choice, I would rather not have been born wealthy, but I never think of giving it up. I can't sell. It doesn't belong to me."

A close friend of the Royal Family, he was a philanthropist who supported both rural and inner-city areas with links to his estate.

But he was also a private man who defied expectations and regularly spoke out on controversial issues.

Born in 1951, Gerald Cavendish Grosvenor was educated at Harrow, where he gained two O-levels, and later went to work on ranches in Australia and Canada.

He then served an informal apprenticeship in property management with a Mayfair estate agent and on the Duke of Buccleuch's 300,000-acre Dumfriesshire estate.

In 1973, when he was 22, he became trustee of the Grosvenor Estate and was forced to abandon his dream of a career as a professional soldier in his uncle's regiment, the 9th/12th Lancers.

He instead signed up to the Territorial Army and in 1994 received an OBE for his work as a volunteer soldier.

When his father Robert died in 1979, he became the sixth Duke of Westminster aged just 27.

He succeeded his father to become chairman of Grosvenor Holdings, the commercial arm of the Grosvenor Estate, and dedicated himself to using his wealth responsibly.

The Westminster Foundation, which manages the estate's charitable giving, has donated to more than 1,500 charitable organisations since 1974, and the Duke was also president of the RNIB for 25 years and president of the St John Ambulance for 10 years.

However, as an outspoken member of the aristocracy, the Duke was also given to acts of non-conformism.

An advocate of change in the Lords, he quit the Conservative Party in 1993 after it proposed the Bill on Leasehold Reform, which would have had a huge effect on his massive London landholdings.

He also paid thousands of pounds to some of his workers to help them meet the poll tax - which he described as "insufferable".

The Duke once said that his life would have been easier if he had sold his estate to live in the Bahamas, but said that "would not be responsible", and also insisted that he would "rather not have been born wealthy".

In 2000, he spoke for the first time about suffering a nervous breakdown and the cloud of depression which overcame him in 1998 after the pressures of businesses and making 500 public appearances a year overcame him.

His family life has been notably private. The Duke married Natalia Phillips in 1978 and they have one son and three daughters.

His wife is a godmother to the Duke of Cambridge and his only son Hugh, is Prince George's youngest godfather.

He also spoke publicly about wanting to ensure his own children were instilled a commitment to using their wealth responsibly.

Speaking about his son and heir Hugh in 1993, he said: "He's been born with the longest silver spoon anyone can have, but he can't go through life sucking on it.

"He has to put back what he has been given."

The Duke of Westminster is succeeded by his son and is survived by his wife, and daughters Lady Tamara, Lady Edwina and Lady Viola.