His marketing director Steve Sharp was having a pint in a London pub when he happened to spot Twiggy, 58, revealed Sir Stuart at the Hay Festival.

“He looked across the bar, saw Twiggy and thought, ‘She is really M&S’,” said Sir Stuart.

“She was a woman of a certain age who looks damn good and is clean, decent and doesn’t do drugs!

“Steve walked up to her, tapped her on the shoulder and asked, ‘Are you Twiggy?’ She said ‘Yes’ and we hired her! It was as simple as that. People relate to her.”