Picnic at Hanging Rock star Natalie Dormer: "I had no desire to get into a corset again”

“I think sometimes people forget that acting is a cardiovascular exercise,” the 36-year-old says when we meet in the air-conditioned splendour of a BBC conference room. “You don’t want to be anywhere near me when I take my corset off because it’s gonna honk.”

Still, it was worth suffering for her art. In Picnic at Hanging Rock, Dormer delivers a brilliantly nuanced performance as Hester Appleyard, a traumatised woman who is trying to reinvent herself on the other side of the world at the turn of the 20th century. The series is an adaptation of a 1967 novel by Australian writer Joan Lindsay, which was also adapted for the big screen in 1975 by Peter Weir.

It tells the story of a group of adolescent schoolgirls who go missing in the Australian bush after a sunny Valentine’s Day picnic at the titular scenic spot. Headmistress Hester is pitched into a feverish world of speculation as the ripple effects of the unsolved mystery begin to spread. The series is directed by the Canadian Larysa Kondracki, who gives the whole thing a lush, magical, almost punk-rock quality.

“People’s imaginations run wild when they think of a group of three young girls and a teacher going missing,” Dormer says. “Is it murder? Is it abuse? Is it dying of malnutrition in the middle of the outback? Have they run away? Your imagination just takes you there.”

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In the midst of mounting paranoia, Hester starts off buttoned-up and cold, sporting high collars and severe hairdos. By the end, “her clothes became slightly more breathable and the hair has to become a little messier,” says Dormer.

“It doesn’t matter whether it’s Blanche Dubois or Hamlet, an actor getting to play psychological unravelling is fun. But it also comes with a cost. Picnic is dark; residue does get left [on you] because Hester doesn’t like herself and she has a lot of unanswered pain and trauma. As an actor you have to, at the end, walk away from that, which isn’t always easy. She was harder to shake off than a lot of [characters] can be.”

Given that Dormer’s previous roles include playing Anne Boleyn in the glossy drama The Tudors, who ended up beheaded; and Margaery Tyrell in Game of Thrones, who married her brother’s male lover for political expedience, then married sociopathic teenager Joffrey Baratheon before dying in an inferno ignited by her mother-in-law, this is no small admission. “This was much harder to shake off than Game of Thrones,” she insists. After playing Hester, she needed downtime and found it through “listening to happy music, exercise, meditation, yoga and running”.

Dormer, who was raised in Berkshire by her mother and her stepfather, a building contractor, always wanted to be an actress. “It was just always there. I wish I had a nice eureka-moment story for you. There really isn’t one.”

She was an only child until the age of seven when a younger sister and brother appeared in quick succession, so she was quite used to playing on her own with the dressing-up box and inventing stories to entertain herself. After attending a local independent school and being offered a place to study history at Cambridge, she failed to get the requisite A-level grades and went instead to the Webber Douglas Academy of Dramatic Art in London.

These days, she lives in London with her fiancé, the television and film director Anthony Byrne, who came to visit her for five weeks on set in Australia while she was shooting Picnic at Hanging Rock. “We’ve always made a point of visiting each other’s sets and watching each other work,” she says.

Recently, they collaborated on In Darkness, a London-set thriller directed by Byrne and co-written by him and Dormer, in which she stars as a blind pianist who overhears a murder. “I wanted to make In Darkness with him because I’d watched him for years and I was jealous of the other actors. I was like, ‘He’s a really great director!’ And I can only assume that he thought I was all right as an actress or he wouldn’t have employed me.”

She also wanted to create her own material because of what she saw as a lack of complex, interesting female parts on offer. When she graduated from drama school, Dormer had no plan (“the only manifesto to begin with was to pay my bills”) but she kept getting offered period pieces. After a while, their charm began to pall. (Picnic at Hanging Rock was the exception to the rule because, she says, “the scripts really grabbed me”.)

“I had no desire, Elizabeth, to get into a corset again,” she says, with disarming candour (she has got a charming habit of remembering one’s name and deploying it to great effect, mid-spiel). “Why I started writing In Darkness [in 2009] was because there was a dearth, as I saw it, of three-dimensional, fleshed out, anti-heroines - you know, flawed female roles.”

There has been a shift, she says, and things are no longer looking quite so bleak. “It’s not as quick as we would all like it to be, of course it’s not, but I’d rather lean into the positive.” As an actress who has always opted for unorthodox roles, often featuring women grappling with some inner darkness, I wonder what she makes of the endemic sexism in her industry, the Harvey Weinstein scandal and the rise of the #MeToo movement?

“The fact that it has to be a point of conversation, I think is part of the evolution,” she says. “I personally don’t want men to feel like they don’t have a creditable place at the table to have a discussion. I know a lot of heterosexual, white men feel like they have no right to talk about this subject and they should just shut up and get out of the room, and I think that has significant challenges… I’m feminist in the true sense of the word – that it’s about equality.”

Dormer is refreshing company: bright, witty and frank. She likes being in her mid-30s (“Who am I kidding? Mid-to-late 30s,” she jokes) because her 20s were riven with “self-doubt”.

“In your 30s, you know so much more about yourself because you’ve been in so many more situations. It’s just literally experience. You’ve f ***ed up, you know? When you’ve done that a number of times, hopefully the idea is you don’t f*** up as badly the next time when you’re presented with a similar situation.”

She goes on to quote the late American playwright, Edward Albee: “If you’re willing to fail interestingly, you tend to succeed interestingly.” And that’s just what Natalie Dormer continues to do: succeed interestingly – in and out of the corset.

Picnic at Hanging Rock begins Wednesday 11th July at 9.05pm on BBC2