I hated history at school - dates and lists of who married whom and who killed whose brother.

As a famous academic said, “history is just one bloody thing after another,” and this ignorant fool can never remember which bloody thing happened when.

But whilst the “when” leaves me cold, the “why” is a different matter, and that’s where A Princess Undone succeeds.

Based loosely around fact, the play provides a sneaky-peeky into the sad life of the late Princess Margaret as she tries to decide what to do with a series of incriminating letters and photographs that have come into her possession.

Set in her apartment in Kensington Palace – sorry, can’t remember the date – the Queen’s bad-girl sister is played with haughty irreverence by Harriet Thorpe (The Brittas Empire, Absolutely Fabulous), who struts around bouncing waspish oneliners back and forth with her mother’s butler, the infamous Backstairs Billy (David Benson.)

It’s unexpectedly funny whilst simultaneously toying with our feelings for this 20th century Royal playgirl.

Evoking equal measures of the gangster and all-round bit of Cockney rough, John Bindon - played with dazzling credibility by Charles Daish - does she meet her match.

Terminally ill, he wants nothing more of her than a friendly “Hello” and a few reminiscences.

Social low-life, he’s the only person who wants her for herself, but Margaret can’t let herself trust him.

The play’s short, sharp and engaging and, having seen it, I’ve a better understanding of why a much maligned character from living memory did the things she did.

Whenever it was she did them.