Andy Warhol photographed her, she feuded with Elizabeth Taylor, she cold-shouldered Princess Diana, and Pablo Picasso - among many others - was obsessed by her.
In her 1950s heyday Princess Margaret was one of the most glamorous women in the world.
With an acerbic tongue and an imperious manner she was the opposite to her restrained, shy sister.
Craig Brown’s latest book Ma'am Darling: 99 Glimpses of Princess Margaret tells the story of her life through 99 pivotal moments.
He says she contrasts markedly with her sister Elizabeth who - to very great effect - has made an art of being dull.
“People can never remember what the Queen says to them, but with Princess Margaret, often because she was so rude, people did remember what she said. She liked saying the wrong thing at the wrong time.”
Although very different characters, Margaret held the Queen in very high regard, he says.
“Whenever she let the side down she felt very guilty.
She even had panicked dreams about it.
“She had this recurrent nightmare that she’d done something desperately wrong, she didn’t know what it was but she knew she’d done some desperately wrong deed which was going to put the Queen in a great state of embarrassment, and so she’d wake up in sweat.
“The only way she could get it out of her mind for the rest of the day was to ring through to the Queen and just hear her voice reassuring her that everything was all right.”
Margaret thought the public had painted her as the “bad sister” and she often gave them what they wanted.
Brown talks of her often-theatrical rudeness. At premieres the star or director might ask her, unwisely, what she thought and she was quite comfortable saying she hated it.
“The Queen would never say that, very few people alive would, but she did say these things.”
Her death in 2002 marked the end of a much more deferent time, he says.
One old friend of Margaret’s told the author, “I can’t believe we let her get away with so much.”
It’s hard to imagine a modern royal calling for a drink floating in a pool, Brown says.
Margaret did so once, and her drinks were brought to her by a fully-clothed servant who waded into the pool where the princess was soaking up rays on a lilo.
Margaret’s love life was famously unhappy. She broke off her engagement to Peter Townsend after a long affair when she was 25 and then met and married Tony Armstrong-Jones.
“She married [Lord] Snowdon. The first two or three years were pretty good, but it was a pretty disastrous marriage, he was a lot more unpleasant than she was.”
The princess and Armstrong-Jones married in 1960 and finally divorced in 1978 after years of heavy drinking, bitter arguments and infidelities on both sides.
Margaret hated to be pitied for her romantic failures, Brown says.
“A lot of her rudeness was a sort a result of her not wanted to be pitied by people.”
Hers, he says, was an interesting life - part comic, part tragic.
“To some extent you can pity her, to some extent you can see her as a comical figure who’s always putting her foot in it, in certain areas you could admire her for having a bit of dash and pizzazz in a family which is fairly lacking in it.”
Margaret was fiercely loyal to the ‘the Firm’ and when Princess Diana famously gave a clandestine interview to the BBC - dishing the dirt on her loveless marriage, Prince Charles’ affair with Camilla Parker-Bowles and her own with James Hewitt - was furious.
“She was very chummy at the beginning, then when Diana invited TV cameras secretly and gave this interview about how terrible her husband was and how unsuited he was to be King, Margaret never spoke to her again.
“She took it worse than any other member of the royal family I think. Even though they both lived in the same building [Kensington Palace] she never spoke to her again. She didn’t want her children to speak to her again, if there was a magazine with Diana’s face on it she would turn it downwards.”
Margaret died in 2002 at the age of 71 after a series of strokes.
Craig Brown has written for satirical publication Private Eye since 1989. He is the author of 18 books and has been a columnist for The Guardian, The Times, The Spectator and The Daily Telegraph. He currently writes for The Daily Mail and The Mail on Sunday.