Until Oprah Winfrey interviewed the Sussexes, perhaps the most notorious Royal TV interview was between Princess Diana and Martin Bashir.

Jonathan Maitland has had a string of hits at Park Theatre tackling subjects from Margaret Thatcher's cabinet, to Boris Johnson and Jimmy Savile, and now takes on this controversial Panorama, which was famously obtained under false pretences.

His latest - a world premiere - is less successful than previous satirical efforts - as Maitland sets himself a hard task of trying to say something new Bashir’s career-ending deception.

With minimal staging, few props, a cast of five and 90 minutes fails to add much of note to the interminable Kensington Palace interview debate.

Yolanda Kettle is the latest actor to get the Di gig. Sporting regulation Sloane ranger jeans, white shirt and iconic hair-cut, she looks the part, but is let down by poor voice coaching, and overuse of the shy head-cock. She does, though, bring out much of the intelligence and wit of this much criticised woman.Ham & High: Yolanda Kettle as Di, Tibu Forbes as Bashir and Matthew Kettle as Paul Burrell in The InterviewYolanda Kettle as Di, Tibu Forbes as Bashir and Matthew Kettle as Paul Burrell in The Interview (Image: Pamela Raith)

Matthew Flynn as oleaginous butler Paul Burrell fulfils the narrator role - he's a fine actor but miscast, but Tibu Forbes is right on the money as Bashir, his concoction of vanity, deviousness, self-righteousness and cowardice is brilliant.

If only he had more to work with. Maitland is an investigative journalist who has done his research, but the script is studded with in-references from Diana's well documented but tragically short life and it feels like a half baked re-heat of existing arguments and media in-jokes.

The first half deals with the decision to go ahead and the prep, the interview, Bashir in full flirt mode and Diana lapping up the faux sympathy and cod understanding. Post interval, Maitland brings back the ghost of Diana to help Bashir reflect on its impact.

“Why” she whispers breathily, “Did they take my voice away?”

It's only in the final fifteen minutes that we get to bigger questions of journalistic ethics - what constitutes consent, who was using who, and how should subjects be safeguarded?

As Diana's ghost questions, was it right for the BBC to seal the tape in the vault?

The Interview runs at Park Theatre, Finsbury Park until November 25.