The Crown casts Natasha McElhone as Prince Philip's close friend Penny Knatchbull

RadioTimes.com has contacted Netflix for confirmation.

Knatchbull, Countess Mountbatten of Burma is the wife of Norton Knatchbull, the cousin once removed of the late Prince Phillip – and she was one of only 30 mourners in attendance at the Duke of Edinburgh's funeral earlier this year.

McElhone joins an already star-studded list of actors for the fifth series, with an all-new cast set to star in the major roles.

Imelda Staunton will be taking over from Olivia Colman in the main role as Queen Elizabeth II, while Jonathan Pryce and Lesley Manville will star as Prince Phillip and Princess Margaret – previously played by Tobias Menzies and Helena Bonham Carter respectively.

Meanwhile other confirmed new cast members include Elizabeth Debicki as Princess Diana, Jonny Lee Miller as former Prime Minister John Major and Olivia Williams as Camilla Parker Bowles.

And there are still some cast members yet to be announced – with no name currently attached to the role of Tony Blair, who is expected to be heavily involved in the series.

We're still waiting for official news on when The Crown’s fifth series will be released, but we do know that it won't be the last season – despite Creator Peter Morgan previously revealing that the show would end after series five.

Morgan’s said in a statement tweeted by Netflix: “As we started to discuss the storylines for series five, it soon became clear that in order to do justice to the richness and complexity of the story we should go back to the original plan and do six seasons.”

He added: “To be clear, series six will not bring us any closer to present-day – it will simply enable us to cover the same period in greater detail.”

The Crown seasons 1-4 are available on Netflix. If you’re looking for more to watch, check out the best series on Netflix or the best movies on Netflix. You can also plan your viewing our TV Guide or visit our dedicated Drama hub for the latest news.