The British actor set out to emulate Meryl Streep but ended up being portrayed as the next Kate Moss. Now, with the tabloid assaults behind her, she talks ambition, Leveson and The Lost City of Z

Sienna Miller is captivating company, but as she talks I find myself thinking about Harriet Harman instead. The veteran Labour MP spoke not long ago about the mysteriously elusive timing of a woman’s prime; when young she is a floozy, too flighty to take seriously, then motherhood casts her to the margins, and by the time her children have grown up she is over the hill. Every woman will recognise the conundrum, but probably none more than Miller.

The Lost City of Z review: Charlie Hunnam slow-burns down the Amazon, leaving Sienna Miller at home Read more

We last met in 2009, when the actor was approaching the end of her 20s, and knew all about not being taken seriously. As Jude Law’s girlfriend, she had become famous overnight at 21, even before her first big film – Alfie – was released. Blonde and vivacious, shimmering with boho chic, Miller was a gossip-column dream, and a series of romances with Rhys Ifans, Josh Hartnett, Jamie Dornan and Balthazar Getty secured her reputation as a good-time party girl. Imagining she was going to be the next Meryl Streep, Miller found herself cast instead as, at best, the next Kate Moss, at worst the scarlet woman.

She is now 35, lives with her four-year-old daughter Marlowe in New York, and is visiting London when we meet. Mesmerisingly beautiful, she retains a playful air of mischief, but is no longer a staple of the celebrity pages, and leads an altogether quieter life. She is, she repeats more than once, only half-joking, “getting old”.

“I think,” she says, “it took a long time to get to a point where people saw me as an actor, and respected that side of things.” Does she feel she’s there now? “I would say I was. I think, within my industry, people think I can act, which is nice, not just put on a coin belt and run down the street away from photographers. That perception of me was really strong and that was hard to overcome. But I think I always did work that I felt was competent, and showed things.”

Within my industry people think I can act and not just put on a coin belt and run away from photographers Sienna Miller

Miller’s body of work includes the Edie Sedgwick biopic Factory Girl, the Steve Buscemi two-hander Interview, and The Edge of Love, in which she played Dylan Thomas’s wife Caitlin and got nominated for a Bafta. More recently, we saw her in the Palme d’Or-nominated Steve Carrell drama Foxcatcher, and in Clint Eastwood’s American Sniper, the highest-grossing war film of all time. Last year she played Ben Affleck’s vivacious but flinty moll in the prohibition gangster movie Live By Night, and in her latest film, the Lost City of Z, based upon a true story, we will see Miller as the Edwardian wife of a British explorer who becomes obsessed with finding a semi-mythical lost city deep in the Amazon.

Even The Lost City of Z’s director, James Gray, has admitted he underestimated Miller’s talent until shooting began, and she is one of the highlights of an otherwise rather plodding film. She had been reluctant to take on another “wife at home” role after American Sniper, and I can see why: most of the movie’s action takes place up the Amazon, while she is back in rural England raising the explorer’s children. She was similarly peripheral in Live By Night, another rather dreary film in which she was one of the best things, fizzing and crackling whenever on screen. Having proven to everyone that she can really act, it must be very frustrating to be confined to minor parts; I wish she was playing leads, and assume she must, too.

“Well, it’s suited me since I had Marlowe to do these parts with these great film-makers, because this took a month, American Sniper was three, Foxcatcher was three weeks. I can, kind of, pop up in these classy things.” School holidays will allow her to co-star with Jack O’Connell in Cat on a Hot Tin Roof at the Apollo Theatre in London this summer, in a 12-week run, but that stretches the limits of the work motherhood will allow. “I do feel frustrated sometimes by the fact that I want to get those roles. I watch films and I know how I’d do it and I want the opportunity. But at the same time you have to strategise in ways that, I don’t know, that I just haven’t done.”

What would that involve? “Oh, shmoozing and doing something to get foreign value.” Foreign value? She sees my blank expression and laughs. “Foreign value. Numbers. You know, someone like Jennifer Lawrence has foreign value. She can get anything financed, she has foreign value for sure.”

Facebook Twitter Pinterest Click to see a trailer for Sienna Miller’s latest film, The Lost City of Z.

I’m curious about what Miller would have to do to accrue some foreign value. “I would probably be the lead in a Marvel film. I’m not averse to doing something like that,” she adds quickly. “I’m not saying that at all. But in order to get to be the star of a film of that sort, for people to bank on you in that way, you need numbers. I can’t get a film financed in the way that you would need to. It’s all about numbers. Which is absolute bollocks, because you can have two movie stars in something and if the film’s crap it can make nothing. The whole way that the industry is set up is numbers, and it doesn’t add up, they’re terrible at the numbers.” Registering my look of commiseration, she smiles brightly. “But I’m not frustrated. I feel quite content.”

Really? “Well,” she explains, “it’s a huge commitment to have the ambition to be playing those parts and to be doing those roles. I don’t know that I have that, the ambition that it takes, the drive that it takes. Yes, I think I have subconsciously shied away from that, I think the idea of that is daunting.”

I went into every audition believing that I could get this, and there was something about that confidence Sienna Miller

Miller grew up in a rather glamorous and affluent transatlantic family, studied drama at the Lee Strasberg Theatre and Film institute in New York City, and has always struck me as utterly dauntless. “I think, from a really young age, I had a real confidence,” she agrees. “I had no doubt in my mind that’s what I would do. I wanted to be, like, in my own mind I was like Meryl Streep. I hadn’t given it much thought, like most things, but it’s like, that was my job, that’s what I wanted to do, and there was never any doubt in my mind.

“It’s actually a really interesting lesson in how much your own confidence and belief can influence things. You see it with Donald Trump. Not that I was like him,” she adds hastily. “I mean, obviously, that’s a really sinister example. But you can absolutely manipulate the situation if you do not allow for doubt within it. I went into every audition believing that I could get this, and there was something about that confidence – people were like: ‘Oh!’ – that I think was disarming.”

I ask if she still has it. “No. It’s whittled away.” Where did it go?

“I don’t know, I think life just sort of happened in quite a full-on way, and I just learned through experience to just become … you know, I just lost some of that innocence and positivity, which is growing up, which is getting older, which happens.” Would she like it back?

“No. I’m just more realistic now. It used to be that everyone was lovely and everything was great and I was so positive and I just couldn’t wait to live and experience.” She smiles. “Now I’m a bit older, and a bit more tired all the time.”

Facebook Twitter Pinterest Sienna Miller, photographed at The Lost City of Z’ press conference in Berlin. Photograph: Collet/Sipa/Rex/Shutterstock

I can’t help feeling that a film about Miller’s life would be as interesting as anything she has appeared in. There is a dark, almost Victorian, subtext to the narrative of moral disapproval that condemned Miller for having about 1% of the fun that young male actors are allowed to enjoy with impunity. Didn’t that make her furious?

“I was always quite good at being aware of the futility of those emotions. What’s the point of perpetuating the frustration that I felt by experiencing it? I didn’t need to sit there getting bitter. But, yes, completely. It is still completely unjustified. Although now I think with social media, I look at young girls who are friends of mine, who are of a similar nature, and they’re so in control of their own image that the media has lost its power. In those days, you were what they said you were, and that was frustrating.”

Miller’s name still appears on clickbait lists like Hollywood’s 10 Hottest Homewreckers. There were rumours of an affair with Daniel Craig while with Law, but it was her brief relationship with Getty, a married father of four who soon returned to his wife, that sealed her tabloid notoriety. Did she internalise the shame she read about?

“Of course, yes. Yes, totally because it was everywhere or I felt like it was. It was very personal, and then you sort of think, well, is that who I am? Then you get older and you’re like, oh, fuck that.”

In 2011, Miller gave evidence to the Leveson inquiry, in which she described being spat at and abused by paparazzi, and after she successfully sued the News of the World for phone hacking she says her life improved dramatically. “I feel more powerful, definitely. It changed the terms. But then I also feel like if anyone wrote anything now it would not bother me. I don’t feel like I could get the shame. I have enough of a sense of my own self and my own life and who I actually am. I don’t think I really did back then, because I don’t think you do when you’re that age, and so I just – it was just an assault, I just felt like I was being blasted with personalities that just perpetuated the behaviour that they wanted to perpetuate. It was a strange experience. But nowadays I feel relatively immune to that kind of bitchy criticism. I don’t feel like I am interesting enough now to be focused on in the way that I was. I don’t want to go out to a pub every night and get pissed. I don’t want that drama.”

In 2012, she became engaged to Marlowe’s father, the British actor Tom Sturridge. The couple split two years ago, but he remains “absolutely my best friend”; the couple live close to each other, spend Christmas as a family and are regularly photographed on days out together with their daughter. “We’re often together at weekends, and he’s there now with his mum and her in my place. It’s all frustratingly amicable from an outsider’s point of view, but really blissful to be in.”

She would, she says, love to have more children – “I’d like an army of them” – but laughs that she has always been hopeless at making plans.

“You can’t change who you are. I’ll always be the same person. I just grew up a little bit, got pregnant and had a kid.”