Tara Palmer-Tomkinson, the god-daughter of the Prince of Wales, has died aged 45 after battling a brain tumour.
The British socialite, who has battled drug problems in the past, was found dead at her home in south west London on Wednesday afternoon.
The Prince Charles and Camilla, the Duchess of Cornwall, paid tribute, saying they are "deeply saddened and our thoughts are so much with the family".
Palmer-Tomkinson revealed last year that she had been diagnosed with a brain tumour in January 2016.
But, in the interview, Palmer-Tomkinson said she had been told the non-malignant growth in her pituitary gland had cleared after treatment.
She said: "I went to the doctors to talk about my latest blood test results when I got back from skiing in January.
"I said: 'What does this mean? Can you translate it?' And the doctor said: 'As I suspected, you have a brain tumour'."
"I got terribly frightened. I started thinking, 'I'm going to die, I'm going to die. I've only got a couple of weeks to live.' Stuff like that."
At the time, Palmer-Tomkinson also revealed that was suffering with an auto-immune disease which had caused tiredness, joint pain and acute anaemia.
A Metropolitan Police spokesman said: "Police were called by London Ambulance Service at approximately 13:40hrs on Wednesday, 8 February to an address in Bramham Gardens, SW5.
"A woman, aged in her 40s, was pronounced dead at the scene. Next of kin have been informed.
"The death is being treated as unexplained. At this early stage, police are not treating the death as suspicious.
"Enquiries into the circumstances are ongoing. The coroner has been informed."
A number of Bramham Gardens residents said they were shocked and horrified by the news.
The blinds were drawn on the flat where Palmer-Tomkinson lived.
Several ambulance vehicles were pulled up outside the address before leaving.
An officer was stationed outside the property and a police car was parked on the street.