The actor, who plays the royal in the third season of Netflix’s hit show, would “reassure” her co-stars when they were directed in certain ways by telling them: “Margaret says that’s all right.”
A source told The Sun that it was important for Bonham Carter to “get her blessing” after meeting the Countess of Snowden at a film premiere as a “fledgling movie star”.
According to reports, Bonham Carter received tips from the Princess’s spirit on how she held her cigarette and cigarette holder.
“She even passed on her advice to cast and crew on set whenever there was a query regarding the princess,” the source added, claiming she would have sessions with a medium who told her: ”Oh yes, Margaret’s here, fingering her pearls.”
Helena Bonham Carter has been contacted for comment.
The Crown returns to Netflix on 19 November. Find everything we know about season three here.