Oscar-winning actress Dame Helen Mirren, who fronts an ad campaign for L'Oreal, said that moisturiser "probably does f*** all".

The moment of candour came while Dame Helen was appearing as a brand ambassador for L'Oreal on a panel at an event in the South of France.

Dame Helen is the face of L'Oreal's "Age Perfect" moisturiser range, and the ads she appears in are not digitally enhanced to lessen wrinkles - something which she insisted on when she took up the role.

"I'm not setting standards for others. All I can do is be who I am. I've always loved make-up," she said.

"I'm an eternal optimist. I know that when I put my moisturiser on it probably does f*** all, but it just makes me feel better.

"I've always said to L'Oreal as well that I will only do what makes me feel better."

The remarks have been compared to the famous comments of entrepreneur Gerald Ratner, who in 1991 gave a speech in which he said of his own company's jewellery: "People say, 'How can you sell this for such a low price?' I say, 'Because it's total crap.'"

The comments sent his eponymous firm into a downward spiral from which it never recovered.

However, L'Oreal is unlikely to meet a similar fate - it registered sales of €25.8bn (£23.3bn) in 2016.

Speaking at the event, Dame Helen spoke of her frustration at the images used by some cosmetics brands.

"It used to drive me crazy that the ads promoting skin products were using pictures of 15- and 16-year-old girls," she said in a speech reported by Campaign magazine.

"As a 30-year-old, I used to look at that and think, what the f*** are you talking about? It was ridiculous. Pissed me off majorly. Advertisers are only just coming out of that, and it's taken them a long time."

A L'Oreal spokesperson was not available for comment.

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