Helena Bonham Carter literally channelled royal ghost for 'The Crown'

"When I heard that they were doing The Crown I thought, 'It's a terrible idea, who'll watch it'?" Helena Bonham Carter, CBE, pauses dramatically on the set of the third season of The Crown (dropping soon on Netflix).

Bonham Carter, who portrays Princess Margaret, is full of self-deprecating wit and arch observations. She raises an eyebrow and continues drolly, "Of course, within five minutes I was hooked."

Laughter follows her words and you get the feeling that the 1.57m Brit with diverse credits, including critically acclaimed films like The King's Speech and A Room with a View and blockbusters like Planet of the Apes and Cinderella, likes to shock.

"I think the royal family are on a high because of this show. It paints them in a sympathetic light. Who knew they could be so fascinating? Princess Margaret was the rebel in the royal family in Season 2. Margaret and Tony [Margaret's husband, Antony Armstrong-Jones, 1st Earl of Snowdon] pulled me in. Especially her. And I am always up for a bit of rebellion."

Explaining her acceptance of the role, she says: "I've played a lot of queens. Each queen is different. I've played a queen mother and I've played the Red Queen - there's a bit of the Red Queen in Margaret.

"It's an extraordinary life to take on. How do you function and satisfy a private life while being perpetually public, not belonging to yourself because you belong to the people? It's your job and you never have a moment off."

The British press hasn't been kind to Bonham Carter, lashing her for her fashion sense and delighting in the break with Tim Burton, her long-time partner and father to her children; her words carry the gravitas of personal insight.

Bonham Carter adds that she consulted a medium in preparation for this role. "I thought I'd try and talk to Margaret and get it from the horse's mouth, as it were," she says, adding: "Admitting that makes me sound even more crackers than I am. And I am crackers. But I thought, 'Why not?' The first thing Margaret said was, 'I'm glad it was you and not the other actress they were considering'."

According to Bonham Carter, Margaret also said: "Get my smoking right, the way I held the cigarette, always with a holder so that my hair wouldn't smell." And then she added: "Remember, the cigarette is a weapon of expression, not just a smoke." Bonham Carter adds: "A lot of her job was to be seen and watched."

The actress says she met the princess a couple of times. "She was friends with my uncle and I met her at Windsor when it was refurbished and she was alone.

"There's a lot of loneliness and isolation in her life that comes with being a royal because nobody approaches you, you have to do the approaching. 

"She approached me because of the family connection and said, 'Yes, yes. You're getting better, aren't you'?"

Bonham Carter's expression emphasizes the impertinence of the comment. "This is about 10 years after I started. I just replied, 'Thank you, ma'am'."

Bonham Carter is not only portraying a well-known figure, she also has to match the performance of Vanessa Kirby, who originated the role in the series.

"I watched Vanessa, not for how she portrayed the princess, because I know I'm an entirely different actor with different physiology.

"But I absorbed Margaret's history. There were things Vanessa did that I wanted to echo. I met a lot of people who knew Margaret and were close to her. Her private life is different from her public persona.

"She was funny, and clever. She was a real wordsmith and did crosswords in minutes. She had a good mind, which I think was a source of her frustration because she wasn't exercising it enough.

"She was like a bored child. If you don't stimulate children enough they end up being self-destructive. She was fun and astute and she had a sense of economy, particularly with silence. She was an enormously complicated person."

The lights come on and Bonham Carter is due back on set. Before she goes, she says: "I took the role because it's a wonderful drama, well written and compelling. With each episode you have a little history lesson."

Then she adds with refreshing honesty: "It's a hit and it's good to be on hits." She can't resist one more truth. "It was a gift of a job, not because it's a show about royalty. It's also about a family existing in an impossible situation. That has such resonance."

• Season 4 of 'The Crown' airs on November 17. 

• Follow Margaret Gardiner on her YouTube channel or on Instagram.