The Queen was said to be "saddened" after Lord Snowdon, her former brother-in-law and the original "royal rebel" died at the age of 86.
During a career that spanned six decades, Snowdon earned a reputation as one of the country's foremost photographers, with subjects as diverse as Marlene Dietrich, David Bowie and, of course, the Royal family. He was also a lifelong campaigner for the disabled.
But it is for his marriage to Princess Margaret, which ended in divorce after 18 years, that he will always be best remembered.
Royal sources said it was too early to say whether the Queen will attend his funeral, which will take place in Wales, though she has always been close to his children by Princess Margaret, Viscount Linley and Lady Sarah Chatto.
Her Majesty may also want to attend to represent her sister, who died in 2002.
Lord Snowdon came from Welsh roots and always regarded himself as a Welshman. His father, the barrister Ronald Armstrong-Jones, was from Caernarfonshire, and it is there that Snowdon, whose title reflects his Welsh heritage, will be laid to rest.
His death was announced by Camera Press, his photographic agent, which said he had passed away "peacefully at home".
Viscount Linley, a bespoke furniture maker, responded to his father's death by paying tribute to him as the man who inspired his career.
He recalled visits to "interesting houses" where his father would pick out "unusual details" and explain to him and his sister why they were significant. He said his father taught him to appreciate craftsmanship and attention to detail through his "clever and effortless manner".
As Antony Armstrong-Jones, Snowdon became the first commoner to marry a king's daughter for 450 years when, in 1960, he and the Princess were married at Westminster Abbey.
Their children have always shared a close bond with the Queen, who provided them with stability when their parents' marriage quickly ran into trouble, partly because of Snowdon's well-documented affairs.
The Queen remained on good terms with Snowdon after her sister became the first royal divorcee since Henry VIII, but had rarely seen him since Princess Margaret's funeral, and Buckingham Palace issued no official statement about his death, other than to say Her Majesty had been informed of it. Insiders said she was "saddened" by the news.
Nicky Haslam, the interior decorator and lifelong friend of Snowdon, said: "He was the epitome of post-war vivacity and young talent, he radiated joie de vivre, that was his great quality, and he never really lost it.
"He and Princess Margaret were the glamour figures of their era; he was a motorbike-riding, devil-may-care photographer, and there was a side to Princess Margaret that longed to be like that herself.
"He was also a first-rate photographer; David Bailey once told me Tony was the best crowd photographer he had ever known. He was a wonderful portrait photographer too. He was doing that sort of modern portrait long before others were, with that spareness - the one of Marlene Dietrich in a cloud of smoke [from 1955] is certainly modern."
Robin Muir, a long-term colleague at Vogue, last saw Snowdon in March when he took him around an exhibition at the National Portrait Gallery celebrating the magazine's centenary.
He said: "I knew things were quite good with him because he ignored everyone else's pictures and just wanted to see his own. He was remarkably proud of his work.
"He was also absolutely hysterical company, and a real champion of the office junior. He would include everybody, no matter how lowly, in what he was doing."
After his divorce, Snowdon married Lucy Lindsay-Hogg, with whom he had another daughter, Lady Frances Armstrong-Jones. They separated in 2000 after it emerged that he had fathered a son, Jasper, by Melanie Cable-Alexander, an editor at Country Life. A fifth child, Polly Fry, came to light in 2004. She had been born three weeks after Snowdon married Princess Margaret, following an affair with her mother Camilla.
He also had a long-term mistress, journalist Ann Hills, who committed suicide in 1996.
His authorised biographer Anne de Courcy said: "Tony once said to me, 'I do like change', and that was a powerful motif in all his frolics. They led him into one emotional car crash after another."
Another of his mistresses was Marjorie Wallace, the former journalist and founder of the mental health charity Sane.
She said: "I saw him just about a month ago and he was clearly quite frail, but he always looked impeccable, dignified and he never complained. I will miss his phone calls, his observations, which were still very sharp and perceptive, and I will just miss having a good friend."