Claire Foy's dark transformation to Lisbeth Salander

She's already reigned as Queen Elizabeth II, Ann Boleyn and Lady Macbeth but now Claire Foy is adopting a very different role with royalty, by playing Lisbeth Salander - the heroine of Stieg Larsson's best-selling trilogy - in The Girl in the Spider's Web, the thriller noir sequel to The Girl with the Dragon Tattoo.

She readily admits that it's the most challenging role she's played and also that she found it daunting living up to fans' expectations and following in the footsteps of both Rooney Mara and Noomi Rapace, who previously starred as Larsson's protagonist.

"I can't deny there's an element of lunacy to willingly reprising a role that means so much to so many people and has already been brilliantly played by both those two," suggests Foy, laughing nervously. "I'm pretty sure some people will think I'm insane for doing this.

"But part of the reason of being an actor is to play things that are wildly different from each other and from yourself, because it allows you to learn and develop," she adds, earnestly. "I've always put myself in positions of greater stress, greater responsibility and greater risk and I'll continue to do that because it's only by changing and challenging myself, like that, that I'm able to further my understanding of what it is I do for a living."

Claire Foy's latest role is a world away from The Crown.

In terms of change and challenge, you couldn't get any more substantive than the transformation from Foy's coy depiction in Breathe or her regal bearing in The Crown to becoming one of the darkest, most distinctive on-screen anti-heroes in The Girl in the Spider's Web. Most noticeable is her physical transformation, with piercings, tattoos, cropped hair and wafer-thin physique rendering Foy as unrecognisable as her predecessor, Rooney Mara, in The Girl with the Dragon Tattoo.

"Yep, I've got the tats and the piercings - at least in the film," she giggles. "Would I have them in real life? Oh, I don't know. It's something I've thought about, but I'm not very good at making up my mind, so I wouldn't want to rush into it and then regret having them there, on my body, forever.

"But it's definitely exciting playing someone who goes against essentially what it means to be an actress, which is to look good, look presentable, be approachable," suggests Foy.

"To play someone who is the antithesis of all that, but is still the centre of the piece and somebody that people sympathise with and care about is brilliant."

Although she's resisted changing her physical appearance after The Girl in the Spider's Web, it's evident that the experience has profoundly affected Foy on a more personal and philosophical level.

Claire Foy as Lisbeth Salander.

"As the other actresses who've played this part will know, Lisbeth becomes a preoccupation because you want to understand her and why she is the way she is. But, ultimately, you can't do that as she's so complex, so unobtainable, fascinating and terrifying," she says. "I was very preoccupied with her."

In fact, Foy concedes that playing the role, where her character tries to rescue - and exact vengeance - for women abused by the men in their lives, has forced her to re-examine her own life, love and relationships, including her marriage – and subsequent divorce – from her husband.

"Playing Lisbeth has been really freeing, because at the same time as I was learning about her I was also learning a lot about myself, women and the relationships between men and women," acknowledges Foy. "There was definitely a period where I went through a phase of not thinking very highly of men and I fully understand the reasons why Lisbeth hates men. I don't think anybody who's been through what she's been through should have any kind of need to look for the best in people, or like men.

"All the things that have gone on [with MeToo] have made people have a good old think about things too, and that's never a bad thing either. For me, in the past year, I have – as have a lot of women and men – really broadened my mind about what I view relationships to be, how they work and how they should be," she reveals.

"But I think that happens naturally when you get to a certain point in life, like me, when you're middle-aged and have a child. You realise you have a choice about whether you accept that this is the way your life's going to be, or else you realise it's an absolute disaster and you need to do something about it, like I did.

"So, yeah, the repercussions of [playing] Lisbeth are bigger than I probably appreciate and ones which I'll only ever realise over time, when I have some distance from this whole experience," surmises Foy, sighing involuntarily as she reflects on her tangled life as the girl in The Girl in the Spider's Web.

LOWDOWN:
Who: Claire Foy
What: The Girl in the Spider's Web
When: In cinemas this Thursday