The 81-year-old was appearing in her role as Erda, the earth goddess, in Das Rheingold at the Royal Opera House in London.

Financial Times reviewer Richard Fairman gave a description of Knox-Peebles's on-stage character.

He wrote: "Erda, the earth goddess, is also on stage the whole evening, played by Rose Knox-Peebles and made up to look quite a fright, though that probably goes with the territory if you have been around since the dawn of time."

But in response to the 12 September review, Knox-Peebles said the look was "all naturally mine".

In a letter to the newspaper, she wrote: "Your reviewer tells readers that Erda, the earth goddess, was made up to look 'quite a fright'.

"This is not so. I wore no make-up - the 'fright' look is all naturally mine."

Knox-Peebles appears on stage naked for most of the performance.

According to her website, she is also drafting a new novel and writing short stories.

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In 2021, entertainment magazine Variety apologised to actress Carey Mulligan for "insensitive language" in a review which appeared to question whether her looks were right for a role.

The publication later posted an editor's note to the top of its review of Mulligan's film, Promising Young Woman, for which she won awards.

It came after the actress said she had seen the article - which suggested Margot Robbie might have been a more obvious choice for the role - and thought it was sexist.