“[Saying] she was only on the plane because of you, and he actually contacted lawyers and was going to sue.”

He replied: “This was back in 1937, when Prince Philip’s sister died in a plane crash flying over to London but the crash happened in Belgium in 1937.

“Now, The Crown’s depiction of it was that she was flying over because he’d been a naughty boy at Gordonstoun and couldn’t fly back to the family for half-term.”

He added: “Prince Philip said [that] this was not the case at the time, and [that] he was close to his sister and they were flying over to see him.

“That’s what upset him at the time.”

The royal expert added the “facts became a dramatised version of events”, adding, that “clearly from a story point of view, [this] made a good element to the story.”

Philip’s sister, Princess Cecilie died, aged 26, on November 16, 1937.

Cecilie also had a daughter, Johanna, who was not present on the plane.

She was also pregnant, at the time of the crash, with her fourth child. It was reported that the child had been born during the flight and also died in the crash.

November 16, 2022 marks 85 years since the deaths of Cecilie and her family.

A sixth season has been confirmed, although no release date has been announced.