I blame The Crown. The glossy, expensively-produced, Emmy Award-winning show has refocussed attention on the Royal Family and in particular the personalities and extracurricular activities of some its more colourful members. Such as Princess Margaret, played in seasons one and two of the Netflix drama by Vanessa Kirby and in the upcoming third season by Helena Bonham Carter, who’s practically a royal anyway.

Of course nobody played Margaret quite like the woman herself – she simply wouldn’t have stood for it – and that fact was underlined in two-part documentary Princess Margaret: The Rebel Royal, which capitalised on the popularity for royal back-stories by digging into the life and character of the Queen’s younger sister and viewing both through the prism of a Britain on the cusp of great social and political change. The same approach that The Crown takes, in other words.

Episode one took us through Margaret's childhood and adolescence, and ended with her marriage to photographer Anthony Armstrong Jones, later Lord Snowdon. He was her entrée into what one talking head referred to as “the Swinging London set”, so we watched her mugging with Peter Sellars in home movies and learned about her bizarre loyalty to Keele University, whose balls and graduation ceremonies she would faithfully turn up to year after year. Swinging indeed.

Last week’s concluding episode, titled Castaway, dealt with the dissolution of her marriage to Lord Snowdon, her dalliances with other men, primarily Roddy Llewellyn, and her life on the island of Mustique, a home-from-home for her when her worth was being questioned yet again by anti-establishment tabloids and bumptious republican MPs (take a bow Dennis Canavan).

It would have been easy enough for the programme-makers to just wheel out archive footage and biographers and let it and them tell the story. Both of those things featured, but they were intercut with cheeky animations and, best of all, in-depth interviews with many of Margaret’s friends, confidantes and admirers (of which Canavan was clearly not one).

Chief among these was Lady Anne Glenconner, a former lady-in-waiting and wife of Scottish aristo Lord Glenconner, who originally owned Mustique. In one of the programme’s best sections, she sat on the sun-deck of a massive, whitewashed Caribbean palace – imagine a scaled-up version of something you’d find on an oligarch’s wedding cake – and chatted with one Princess Lowenstein, a neighbour, about how royals should only ever marry their own and what happened when Mick Jagger came for Hogmanay.

And what did happen? He dressed up as a doctor and had all the women at the party queueing up to be examined by him, of course.

“Did Margaret?” asked the interviewer, barely able to keep the excitement out of her voice.

“I think she did,” replied the titled lady. “She was up for anything”.