Helena Bonham Carter got the late Princess Margaret's "blessing" through a medium before playing her in 'The Crown'

Helena met Margaret - who is Queen Elizabeth II's sister - in person at a movie premiere when the actress was still a "fledgling movie star", and felt it was "especially important" to get her blessing.

A TV insider told The Sun newspaper: "Helena was just a fledgling movie star when they met at a royal movie premiere and the fact she made such an impact on her made it especially important to get her blessing.

"But she got much more, including little acting tips, such as using her cigarette and cigarette holder to express herself in The Crown, just as she did in real life.

"She even passed on her advice to cast and crew on set whenever there was a query regarding the princess. Helena would reassure them: 'Margaret says that's all right.' "

Previously, it was revealed Helena had received acting tips from Margaret, because she believed the key to "perfecting the role" was to "constantly contact" the royal.

Another insider said last year: "Although many of us might feel like laughing at what Helena is doing, it's actually a reflection of how seriously she's taking the part.

"As someone who has a very strong spiritual side, she firmly believes that she is getting tips directly from Princess Margaret.

"And she's convinced the best way of perfecting the role is by constantly consulting the royal, through the psychic, as filming of the series advances."

Fans of 'The Crown' will get to witness Helena bring Margaret to life on screen opposite Olivia Coleman as Queen Elizabeth when the show airs its third series in November.