The Crown, which follows Queen Elizabeth II's reign and includes a young Prince Harry, as well as featuring some of the incidents he has written about in his autobiography Spare in later series, has been criticised over its historical accuracy.
Streaming service Netflix faced calls to add a disclaimer at the beginning of episodes stating that it is a work of fiction - and now Harry, who has given various interviews this week on the importance of telling his truth in Spare - has said he has done his own fact check for accuracy on the series.
During his interview on The Late Show in the US about his memoir, CBS presenter Stephen Colbert asked: "You’ve watched The Crown, right? You’ve got to have watched some of The Crown, right?"
Harry looked at the audience and paused briefly before saying: "There’s people laughing at that – yes, I have actually watched The Crown."
"The recent stuff or the older stuff?" Colbert asked.
The duke replied: "The older stuff and the more recent stuff."
Colbert continued: "Do you fact-check it while you watch it?"
Harry then jokingly pretended to take out a notepad and mimed taking notes before laughing: "Yes, I do actually."
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He pointed to a copy of his book and added: "Which, by the way, is another reason why it’s important that history has it right."
The Crown has starred Claire Foy and Olivia Colman as the Queen, with Imelda Staunton currently in the role.
Its most recent cast also includes Jonathan Pryce as Prince Philip, Dominic West as Prince Charles and Elizabeth Debicki as Princess Diana.
Matt Smith, who played Prince Philip in the first two series, has previously hinted at Harry watching the show and revealed he had once been addressed by him as "granddad".
Speaking on The Today Show in the US, Smith said: "I met Harry once, at polo, which sounds a bit grand, but it wasn’t that grand.
"And he rocked up to me and went 'Granddad'."