Society photographer and Staffordshire landowner Lord Lichfield died today.
He passed away at 4am after suffering a stroke yesterday.
A statement released by Lichfield Studios said: "The Earl of Lichfield died peacefully early this morning."
The 66-year-old photographer, a first cousin once-removed of the Queen, was staying in the Oxford area with friends when he was taken ill.
He was taken to John Radcliffe Hospital in Oxford where members of his family were at his bedside.
The Queen was "deeply saddened" by his death, Buckingham Palace said.
A Buckingham Palace spokeswoman said: "It's a private matter. The Queen is deeply saddened and will be sending private condolences."
Lord Lichfield, one of Britain's best-known photographers, was taken to hospital after suddenly falling ill.
He underwent tests, was diagnosed as having had a stroke and admitted to the Stroke Unit.
A spokeswoman for his photographic agents Camera Press said yesterday that members of his family were with him at the hospital.
His long-term partner was Lady Annunziata Asquith.
Lord Lichfield was often called on by the Royals to take their official family group portraits.
In July 1981, he was presented with the formidable task of shooting the official photographs at the wedding of the Prince of Wales and Lady Diana Spencer.
One of his most famous images, which he had recently recreated, was the naked pose of Sixties singer Marsha Hunt with a giant afro for the musical Hair.
He worked for Vogue and his career as a photographer spanned more than 40 years.
He was awarded fellowships of both the British Institute of Professional Photographers and the Royal Photographic Society and was a great supporter of photography's digital revolution.
Other stars he captured on camera ranged from Joanna Lumley and Michael Caine to an intimate portrait of Mick and Bianca Jagger at their wedding in St Tropez in 1971.
Born Thomas Patrick John Anson on April 25 1939, Lord Lichfield was the son of Viscount Anson and Princess Anne of Denmark, who was the Queen Mother's niece.
He inherited the Earldom of Lichfield from his paternal grandfather.
He had three children with his now ex-wife Lady Leonora Grosvenor - a son, Tom, and two daughters, Rose and Eloise.
Former royal press officer Dickie Arbiter told the Live With Alastair Stewart Show on the ITV News Channel: "The death has touched the Queen deeply. Patrick was very close to the Queen.
"He was Patrick Lichfield first and Lord Lichfield second.
"He was passionate about his work, and his work was more important to him than any hereditary title.
"He had the Royal Family's trust, so if he said 'Stand on your head' they would do that.
"And one of the good things about him was that he was not a gossip, like a lot of people do tend to be, either those very close, or those who think they are very close."
Lord Lichfield's friend and colleague Ian Lloyd branded him a "revolutionary" royal photographer.
"He was totally charming, very down to earth. He had access to the Palace but he did not make a very big thing about it," Mr Lloyd said.
"He was very discreet and was not a man who attracted huge scandal. He could have made quite a lot of money from talking about his royal connection.
"But he never sold stories.
"He was a revolutionary royal photographer. Before him the photographs were very incredibly posed."