Ask anyone who has ever worked with, interviewed or just spoken to Saoirse Ronan, and one word will always pop up, right after “lovely” and “humble”. Professional. Having landed her first acting gig at age nine on the Irish TV show The Clinic, the 24-year-old actress has grown into a consummate professional. Having starred in films like Atonement, Brooklyn, The Lovely Bones, The Grand Budapest Hotel and last year’s critical smash Lady Bird, Ronan’s professionalism has not only garnered her a Golden Globe award and two Oscar nominations, but a reputation for being incredibly talented, focused, and a canny player of the Hollywood game.

In interviews, she is always warm and personable, correcting the pronunciation of her name for the millionth time without an ounce of frustration, and going along with jokes with great humour (even that goddawful Oirish SNL skit). She is also brilliantly adept at dodging questions about her personal life, never giving too much away, but never making it look like she’s being deliberately evasive – like only a pro can.

But what’s it like being a young woman in your twenties – a time where most people are making absurd mistakes and figuring out what they want to do with their life – when you’ve spent the past decade establishing yourself as an actor and public professional? How do you define yourself beyond work you started when you were nine?

“I think I’m still figuring that out!” laughs Ronan, sitting on stage at the Google Foundry in Dublin. But she understands the question, having asked it of herself already. “I got to a point a few years ago, and it’s something that I’m still aware of, that I love the work but I thought, ‘Is this sort of all I can do?’ It’s great to have work, but you don’t want to just be defined by that one thing either.”

Instead of succumbing to the very understandable public breakdowns and identity crises that some of her famous peers have gone through, Ronan allowed herself to embrace those feelings calmly. She explored what she needed to do to bring more balance to her life, which involved spending more time with friends and having more fun.

“It was interesting for me to see when I did reach that point and start to give the rest of my life a bit more time, how relaxed I became at work,” she says. “Work is something that I do take very seriously when I’m doing it, and I’m definitely a perfectionist.”

Nonetheless, Ronan tries to avoid feeling self-important about it, saying she adored Olivia Colman’s endearingly humble and understated acceptance speech at the Golden Globes this year: “I like that attitude of, ‘I just learn the lines and show up and do it.’”

Instead of approaching it with the award-baiting ‘I Am Acting’ attitude dripping off some actors, Ronan prefers to embrace the experience as a whole.

“I almost go at it from a child’s approach, because it’s play, it’s imaginary, and there’s something really wonderful about being able to disappear into another world. You have to remember that.”

Her latest role is the titular Mary Queen Of Scots, opposite Margot Robbie’s Elizabeth I in Josie Rourke’s historical drama. For Ronan, the chance to play a role that explored power and femininity was always irresistible – but its personal resonance has changed since she first read the script.

“I had signed up to it when I was 18 and we made it when I was 23, so there was about five years in between,” she explains. “And loads of people have been asking me if I had made it at 18, would the film have been different, or would I have been a different Mary – and I really think I would have been. I’m so happy we made it when we did, because it was so important to show that Mary expected to be the leader that she wanted to be, and expected to get that respect from the people around her. But she was a woman, and she enjoyed being a woman. And I also enjoy being a woman. And that’s something that was still new for me, at that age, in my early 20s.”

Ronan was frustrated when she hit her early twenties and discovered that despite her impressive filmography and obvious talent, there just weren’t many interesting and well-rounded parts for women her age.

“That was such a frustration that I had in my late teens,” Ronan admits. “For some reason we weren’t being written about, and I didn’t know why. And that was the stage when I started asking, ‘What’s going on, our voices are important!’ And everything is happening to you, it’s such an exciting and scary time - which was exactly the same for Mary Stuart. So to highlight that time in a woman’s life and honour it by playing someone real who experienced that was really exciting.”

Rourke’s film has received some criticism for historical inaccuracies, such as an onscreen meeting between Mary and Elizabeth that never happened, but it’s also being rightly lauded for its representation of the embodied female experience. In the film, Mary’s power and lack thereof often manifests through how her body is viewed and treated by others. She is unapologetically sexual and sensual, but also experiences physical and sexual violence. However, it’s not just the extremes, but the everyday that Rourke wanted to represent onscreen. The director fought to include a scene that shows Mary menstruating, which is still – somewhat pathetically – a taboo in cinema.

“I can’t think of many other films that have shown that,” Ronan says. “Even when I was younger, nobody around me would say the world ‘tampon’ or ‘period’ or anything like that.” Despite her matter-of-fact tone, there are, predictably, a few shocked giggles from the audience, proving her point. “Few nervous laughs out there,” she notes wryly.

“Anyway, it’s a new thing to show something very natural and very, eh, regular on screen,” she says, laughing at her own pun. She is aware that Rourke convinced anxious studio executives to keep the scene in the final cut of the film, and agrees that probably would not have been the case with a male director. “There’s an innate understanding of a very particular female experience that you can only get from another female, obviously. But also just to think that that experience itself has some importance; that if someone doesn’t go through that, it could often go overlooked. And for me, I hadn’t even really thought about it before. And thought, ‘Oh yeah, it is really important to show that in a film.’”

For Ronan, it’s more about sensibility than gender, and she appreciates writers and directors whose vision isn’t shaped by traditional gender roles, but empathy and curiosity.

“At the end of the day, I’ve worked with female directors who are quite masculine, or others who are more sensitive and delicate –-and the same with men. The director I’m about to work with, Francis Lee, is the most sensitive, lovely man, and he’s about to direct two women in love in a film. I don’t think I could be in better hands. So it depends on the person. But certainly with moments like [the period scene], it’s wonderful to have someone come in and say, ‘No, let’s show this.’”

How does she feel about inclusion riders and other incentives to promote women writers and directors?

“I would hope that it happened naturally,” she sighs disappointedly. “Though I know it hasn’t and that’s why people are pushing for it. I’ve been very lucky in that the first director I worked with was a woman, and I’ve continued to work with female directors since then. So that hasn’t been an unusual thing for me. But there just needs to be more of them. So that – just like with the period thing – they can represent their own stories and stories like people like them a bit more. And to be honest, I don’t know why anyone wouldn’t want that. It just means that when you go to the cinema, you have more of a choice. There’ll be a little bit of everything. I think it will start to change – I think it already has started to change.”

Mary and Elizabeth are presented as two women going through similar experiences of trying to maintain their power and command respect from the men around them, though they approach this very differently. The pressure to have a child that will be an heir means that the women’s bodies, including Elizabeth’s virginity and Mary’s sexuality, are constantly up for public scrutiny. Ronan was filming in the lead up to Ireland’s abortion referendum – did the themes of body politics and women’s right to bodily autonomy feel more prescient because of the political and social climate at home?

“It was something we were conscious of,” she reflects. “For me as an actor, the performance always needs to come from an emotional place. Hopefully, it can then organically become something political, or something that is a statement. The Repeal vote happened after we had made the film. And so after being immersed in that world for a few months, where you’re playing a character who has ultimate power that will be taken away from her at the drop of a hat as soon as she has a kid, has a son – which it was – it just made it even more personal. Even though of course I’m very protective over my own body anyway, to play somebody who didn’t have those rights, who wasn’t afforded that, made it even more personal somehow. It made it clearer that that is something to fight for.”

The audience at the Google Foundry is primarily made up of young people and professionals in their twenties, and Ronan is asked can she share some tips for success – but as ever, she is humble and self-aware in her answer.

“There is a lot of it that is down to luck,” she says. “Anyone who is doing well at what they’re doing, regardless of the industry, will say that there was one person – one person who believed in you, who championed you, who gave you a chance. And I’ve had those people. I was very lucky that I had a Dad who was already acting, so I was introduced to that world at an early age. But there are also people like John and Ros Hubbard who are casting agents, and I wouldn’t be here if it wasn’t for them. But once you start working, honestly a really good work ethic is what will get you through it. I really admire people who give it their absolute best. And surround yourself with really great, ambitious people who will challenge you and make you work harder.”

Not that she needs the reminder – as she mentioned, Ronan is set to star opposite Kate Winslet in Francis Lee’s Ammonite, as well as playing Jo in Greta Gerwig’s remake of Little Women. In addition, she’s just started working on Wes Anderson’s The French Dispatch, a musical set in France after World War II. But in an ideal world, what would her dream role be? “I would pay to be in the sequel to Bridesmaids!” she says with the wide-eyed enthusiasm of an obsessive fangirl. “And I think it’s about time someone made a film about Countess Markievicz. I’d like to play her. Or Queen Medb. So I can just use my own accent!”

Mary Queen Of Scots is in cinemas now.