Mark Shand, the brother-in-law of Britain's Prince of Wales, has died after falling outside a New York hotel bar and suffering a head injury, police said.
Shand, 62, the brother of Prince Charles' wife, Camilla, Duchess of Cornwall, was in New York for a charity auction at Sotheby's.
He had arrived at the Gramercy Park Hotel's Rose Bar just before 1am on Wednesday accompanied by a relative, police said. He went out to smoke a cigarette at about 2.30am and fell backward as he tried to re-enter through a revolving door, they said. He was taken to a hospital, where he was pronounced dead at 11.25am, police said. The cause of his death will be determined by the medical examiner's office.
Shand, who was chairman of an Asian elephant conservation charity, was known for his work as a travel writer and conservationist. He wrote several books including Elephant Tales and River Dog: A Journey Down the Brahmaputra.
British royal officials at Clarence House said Camilla, Prince Charles and her family members were "utterly devastated by this sudden and tragic loss".
"Mark Shand was a man of extraordinary vitality, a tireless campaigner and conservationist whose incredible work through The Elephant Family and beyond remained his focus right up until his death," it said.
Camilla and Charles are due to tour Canada next month.