Lady Glenconner - who also a childhood friend of the late monarch and maid of honour at her coronation - has insisted that the royal drama gives an "unfair" portrayal and is a "complete fantasy".
WATCH: The Crown season five on Netflix - official trailer
Speaking to BBC Radio 4’s Woman’s Hour, the socialite, 90, said: "It's so irritating. I don't watch The Crown now because it just makes me so angry. And it's so unfair on members of the Royal Family." She added: "The trouble is that people, especially in America, believe it completely."
Lady Glenconner highlighted certain storylines as being "completely untrue". In series two, a school-age Duke of Edinburgh is presented as being indirectly responsible for the death of his sister Cecile in a plane crash in 1937 - which she was "terribly hurting".
Lady Glenconner is a childhood friend of the late Queen and Princess Margaret
In season three, Lady Glenconner is herself shown as having a conversation with Princess Margaret where they discuss the virtues of various men. Of the scene, in which she is played by Nancy Carroll, she said: "I mean, of course that never happened."
The daughter of the 5th Earl of Leicester previously gave actress Helena Bonham Carter advice on her portrayal of the late royal, the role of which has gone to Lesley Manville for the new season five that arrived on the streaming platform earlier this month. She said: "She came for about two hours. I told her how Princess Margaret smoked, how she walked.
Lesley Manville plays Princess Margaret in season five
"I saw Helena after she'd been in The Crown and she said, 'What did you think?' And I said, 'Well, rather disappointed.' And she said, 'I know. But the thing is, I'm an actress, and I have to do what's written for me.'"
Netflix has insisted that the series has always been described as a “drama based on historical events”. They added a disclaimer to the marketing for the new series, claiming that it is a "fictional dramatisation", "inspired by real-life events".
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