Appearing on The Graham Norton Show, Bonham Carter talked about how she used a psychic to speak to the late Princess Margaret in preparation to play the royal in the third series of The Crown, which launches on Netflix later this month.
"I did meet a psychic, who's a friend of mine, and I was seeing her," said Bonham Carter. "She does healing. She does other things, but she also has a talent for mediumship and as I was seeing her for something else, she said, 'Oh, Margaret is here. Does that mean anything?' and I said, 'Yes, it does.'"
Bonham Carter explained she was being considered for the role of Princess Margaret at the time. "I said, 'Well, yeah... If you've got the horse's mouth in the room, you're not going to say no,'" she said. "I said, 'Yeah' and I asked, 'Would you mind if I played you?' She did say, 'I think you're a better idea than the other actor.' They never told me the other possibility."
"It was a very typical Margaret thing," she added, explaining that when she had previously met the princess when she was alive, she “had a way of sometimes complimenting you and putting you down at the same time. And the fact that she said, 'Oh yeah, I think that you're better than the other.’ It's like you never knew where you were with her."
Bonham Carter added that the spirit "came through with another note," for the actor to "get the smoking right".
The ghost apparently said: "I smoked in a particular way and always remember that the cigarette holder is as much a weapon for expression as anything else and that was a good note."
When Bonham Carter turned to her co-star Olivia Colman and asked her if she believes in "talking to dead people", Colman replied: "No."
The Crown season three begins on Netflix on 17 November.