Before there was Meghan, before Kate’s bump, Pippa’s rump, Fergie’s indiscretions or the tabloid gift-that-keeps-on-giving which was Diana, the press devoured Princess Margaret as a constantly watchable icon of fashion, self-indulgence and vigorous impropriety.

While she maintained a home and louche lifestyle in the Caribbean, one of her followers was an ex-con, ex-actor, possible murderer and hard drinker John Bindon whose party trick was to thread five half-pint beer mugs onto his semi-erect todger and go ‘look, no hands’.

Bashing them together thirty years on, in 1993 when Charles and Diana have separated and Margaret is sorting through her mother’s personal papers, is a random act of theatre which works best if you’re already pretty familiar with some source material, such as Craig Brown’s enjoyably salacious 2017 book ‘Ma’am Darling

For anyone else, this may be a Yorkshire pudding of a play: crisp round the edges, with some smart putdowns and occasionally crackling jokes from HRH, but a soggy centre with two eggy attempts at blackmail where it’s just not clear what she is alleged to have done.

There may have been more to the Queen’s sister than a put-down stare, chain smoking and a fondness for Famous Grouse Scotch, but despite Felicity Dean’s fine glint-in-the-eye portrayal of both the camp and the stern Princess, there are no fresh insights in Richard Stirling’s script.

Saturday’s audience at the Park was definitely old enough to have lived through the saga, but didn’t feel licensed to react to the jokes.

On tour, Stephanie Beacham played Margaret. Maybe what’s missing is that touch of ‘Dynasty’ glamour.