The Crown writers have had to change the script for season six, after it was revealed that Gillian Anderson will not be returning.

The 54-year-old actress previously played former prime minister Margaret Thatcher on the show but after scheduling conflicts prevented her from reprising the role, The Crown’s writers had to hastily rewrite some of the scripts.

A source told The Sun newspaper: “Gillian’s portrayal of Thatcher was met with global critical acclaim and she was a huge asset to The Crown.”

“It had been hoped she would be able to make an appearance in scenes around the golden wedding, but sadly that has not been the case due to scheduling issues.”

On The Crown, Margaret Thatcher (Gillian Anderson) and her husband, Denis (Stephen Boxer), dress to impress for dinner with the royal family. Photo / Netflix

As ever with the series, clever scripting will mean viewers will be none the wiser.

”It’s been another blow for producers in what’s already been a fairly dogged production.”

Anderson’s portrayal of Thatcher in season four won her an Emmy and a Golden Globe.

Meanwhile, Anderson previously insisted that The Crown has made the royal family “more internationally loved, celebrated and understood”.

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She told Total Film magazine: “It’s a drama. There’s a lot of researchers involved and a lot of people checking and double-checking and triple-checking.

The Crown has been deemed "truthful without being accurate" by some critics. Photo / Netflix

”There’s a lot that has not been written about that could be written about.

”And if you knew the difference in those, you’d see there is a great deal of kindness and restraint.

”And I think at the end of the day, there are incredibly compassionate and well-rounded takes on human beings.

”And what you’re left with is properly, maturely drawn, complex characters. And there’s a lot that’s in there that one has to say; if you didn’t do it, we wouldn’t be writing about it.

”I think the whole family is more internationally loved, celebrated and understood in a way that they wouldn’t be were it not for the show.”