Saoirse Ronan is going on holidays. "I'm off to Greece," she tells me, "and I'm really looking forward to it - it'll be nice to slow down." She is, in fairness, due a break. Over the past 18 months or so, she's made three major films back-to-back - Lady Bird, On Chesil Beach, which is out this week, and Mary Queen of Scots, a historical drama co-starring Margot Robbie that will be released in December.
Saoirse was still working on that film when Greta Gerwig called to let her know Lady Bird had gone down a storm at the American festivals, and that her services would be required for an awards campaign. It became one of the most talked-about movies of the year, winning wide acclaim and earning the actress an Oscar nomination and a Golden Globe. In the midst of the awards season madness, she also hosted America's most iconic TV comedy show, Saturday Night Live, alongside U2.
You'll not be surprised to hear she's excellent in On Chesil Beach. It's based on a novel by Ian McEwan. It was adapted for the big screen by the writer himself, and he and Ronan go back a ways. She first met him on the set of Atonement, Joe Wright's 2007 film, which shot the actress to fame and earned her first Oscar nomination aged just 12.
McEwan described her performance in Atonement as "remarkable - she gives us thought processes right on screen, even before she speaks, and conveys so much with her eyes".
Was the writer always keen on Ronan starring in On Chesil Beach?
"He says he was," she says with a laugh. "No, I think he was. I was too young when they first thought about doing it, and you know what films are like - they can take two years or they can take 10 to pull together - so I was about 16 when they first wanted to do it, and by the time it happened I was the right age. I said to Ian I was just sabotaging the film for all those years until I could do it."
On Chesil Beach is set in the early 1960s. Saoirse plays Florence Ponting, an Oxford graduate and talented classical musician who's just married an amiable but intense young man called Edward Mayhew (Billy Howle).
On their wedding night, the couple repair to a fusty hotel on the Dorset coast. They're virgins, and after enduring the purgatory of a 'silver service' meal doled out to them in their room by two supercilious waiters, Florence and Edward go to bed for what ought to be a magical moment. Instead, it's a nightmare.
The film's most compelling scenes are those excruciating moments in the bedroom when the young couple flounder mortifyingly as they clumsily attempt to copulate.
Was it hard to get inside the mind of a character from that prudish place and time?
"In a way, yes, because it's something that not as many people have an aversion to now, but I do think there's still the issue of a young person walking into that situation and not having a clue what they're doing," says Ronan.
"Maybe not a wedding night, but it was still her first time, you know, and I don't think the fear around that has entirely gone away.
"With Billy's character, Edward, you can see that he feels emasculated and full of shame. He's embarrassed, and Ian told us that Edward goes into that wedding night expecting it to be this like big, explosive, earth-shattering night of love-making, and it's just not that and it probably isn't for most people first time.
"There was this massive amount of pressure being put on them to deliver, and I don't think that's changed all that much."
We love to give out about how bad foreigners are at Irish accents, but Irish actors haven't exactly covered themselves in glory any time they've attempted an English one.
In On Chesil Beach, Ronan's is extraordinarily good, and Florence's stifled, careful upper-class accent seems to complement her sensual recessiveness perfectly.
"It's the first thing I think about always, how a person is going to sound, because it says so much about you: how you interact with people, how forward you are, how reserved. In this film, at that time, her accent was really telling, and it gave me something to hang on to at the start."
Saoirse went straight into On Chesil Beach after Lady Bird, which must have been exhausting. "They actually overlapped," she says. "I had finished most of Lady Bird on a Saturday, then I flew to London, went straight into rehearsals on Monday morning, rehearsed from Monday to Thursday, then Thursday night I flew back to New York, finished Lady Bird at like 5am on Friday morning, then I got back on a plane and I started On Chesil Beach on Monday. It was a killer for those first couple of weeks - it was brutal."
Did the success of Lady Bird take her by surprise?
"Oh yeah, we didn't expect it at all. Not because we didn't think the film was good enough, but I think it was just partly that you don't ever expect that from a film that you're in - a tiny little film that you made for, like, no money.
"I was doing Mary Queen of Scots at the time, and they were taking Lady Bird to the Telluride Festival, but I couldn't go. They came back and said, 'We're going to do an awards campaign because everyone really loves it', and I was kind of shocked. So then I ended up going straight into Press for it and I did that for six months."
Saoirse first met Lady Bird's writer and director Greta Gerwig at the Toronto Film Festival a few years back, and Gerwig asked her to read through the script with her in her hotel room.
"I'm such a big fan of hers," she says. "I love her so much, so I was really excited meeting her, but I was quite nervous too.
"I also didn't know if it was an audition. I was like, 'Do I have the part or do you want me to prove to you?' We read through the whole thing and she was like, 'I'll do everyone else's parts', and I read Lady Bird. As I was reading it, I was thinking, 'Is this what she wants me to do?' It's a comedy, and that's my favourite genre, so I didn't want to mess it up. She said later that she realised I was right for it there and then."
Gerwig's tale of a rebellious teenage girl and her temperamental mother is based in part on her own early life in Sacramento, and Lady Bird was mainly shot in California's capital.
"Her best friend's grandmother had a role in the film and everyone seemed to know Greta. We'd be shooting in the street and people would stop their cars and say, 'Hey Greta, my dad says hi'. It was such a tight community and I think she was delighted to be shooting there," says Ronan.
The finished film went down a storm at the Golden Globes in January, winning Best Picture Musical or Comedy, and Best Actress for Ronan. "It was a shock," she tells me. "I'm used to just being nominated and not winning - my loser face is finely honed. When I won I was like, 'Oh no, I actually have to talk now...I have to speak'. Then, when you go up on stage, they have this huge widescreen TV directly opposite you, and it's flashing these big red numbers at you, like '45 seconds, 44 seconds!' And you're like, 'Oh God' and you forget everything."
She says that "everybody knew" Frances McDormand was going to win this year's Best Actress Oscar, which nicely took the pressure off. In her acceptance speech, McDormand asked all the female nominees to stand up before memorably championing women in the film industry, and asking why they had to fight so much harder to get things done.
"We got a hint the day before that she was going to do something special. My publicist had said to me, 'I just want to let you know that if Fran tells you to stand up at some stage tomorrow night, stand up', and it completely went out of my head. And then when she won she was like, 'Okay, I'm going to ask everyone to do something', and when she got everyone to share that with her, I just thought, 'What a cool move'."
Although she's been acting professionally since she was nine, Saoirse's never ventured onto the stage until late 2016, when she starred in an acclaimed production of Arthur Miller's The Crucible on Broadway. What was that like?
"Terrifying. I mean it was such a privilege to do that play, and it's so good and everything, but the next time I do a play I'd like to do something in a smaller theatre. The voice was the thing I worried about most - would it be big enough? - and that was the only thing I'd recommend people go and train for if they hadn't done theatre before, because it's different, it's a proper instrument."
The whole business of stage acting was different. "The lens is going to pick up everything that you think, you know - if you're feeling something sincerely, it will find it. Whereas the great thing about doing theatre, and it definitely helped me going into Lady Bird and Mary Queen of Scots the following year, is that you really do have to be in touch with your body. Physicality is so important when you're on a stage and you need to know how to tell a story with movement, not in an artsy-fartsy interpretative dance kind of way, but just it's important to know how to be in your body.
"I had a fear with the voice and I also had a fear of having to act big, because I really didn't want to do that. That kind of scared me. But I think the thing that can help combat that is using your body a bit more, and then you don't have to go all big." She got rave reviews, though. "Yeah," she says quietly. "That's good."
Less glowing on this side of the Atlantic were reactions to her appearance on Saturday Night Live, when her participation in sketch about a pair of bumbling Aer Lingus hostesses got up certain patriotic noses.
"I was surprised. One of the brilliant things about the Irish is that we can take the p*** out of ourselves. I love Aer Lingus, I've flown with them since I was a child, and one of the most emotional moments for me about going home is when I get on an Aer Lingus flight and I hear the Irish accent and I'm surrounded by people from home. So it was never done in bad taste, and you also have to remember, it's a comedy show. They poke fun at everyone and they poke fun at themselves, and we had sketches about Brooklyn as well and I wasn't offended. It was all a bit of craic."
Doing Saturday Night Live was "daunting, but an amazing experience. You've got these great comic actors, like Kate McKinnon, but also all these writers, about 30 of them, who are working 'til like 5am finishing sketches. Everyone who's done it had just said to me, you have no control over what's going to happen, and you kind of just have to go with it, which was kind of a difficult thing for me because I was like, 'But we need to have a plan!'. But once you do that you're fine. The song was the only thing I was nervous about because it's so difficult, but once I got through that I was fine. And it also helped having the band there, U2, that made me feel much more relaxed."
I've interviewed Saoirse before, and am always struck by her calmness, her unfussy self-possession and her quiet determination never to allow herself to be sidetracked by the nonsense of celebrity. When I spoke to her in 2013, she told me she didn't think of herself as famous, and could walk about unrecognised in New York. Is that getting harder now?
"I am getting recognised much more over there now," she says. "Because of Lady Bird, I think. But I still have that thing in my head though where I think, you know, Justin Bieber is famous, and that's a level of fame that I don't feel a part of at all. So because I don't read any articles about myself - sorry Paul - and I don't look at any photos of myself or interviews, I'm kind of able to detach from it almost completely. The only thing that I have noticed now is that I do get recognised more. I've always been recognised at home, but it's happening an awful lot more when I'm away."
Things don't always go swimmingly for child stars in adult life, but for Saoirse, starting young seems to have helped her stay level-headed about the job she does and the distractions it can bring. "I think the fact I started when I was so young has helped me in a way, but I'm also very, very lucky that I have parents who weren't fazed by it, in particular my mam, who had spent years supporting my dad, because he's an actor too. He started out in the theatre in New York and had ups and downs and had times where he wasn't working and where he was working a lot, she saw the pitfalls and the highs and lows of that.
"Also, from the very beginning, it's only been about work, that's always been the only focus for me. That's what I do this for, that's what I care about, and when you know why you do what you do, it's makes everything much clearer. So if you do start to get recognised or whatever, it feels like it's almost not a part of what you do."
She has, she says, always been encouraged to have cautious expectations about her career. "Even now, I'm of the mindset that everything's really good at the moment, so I'm going to appreciate it now, because there will be times when maybe it isn't. I hope to be working in film always, but you never know."
On Chesil Beach is in cinemas now
In an exclusive interview, Golden Globe winner and Oscar nominee Saoirse Ronan talks to Paul Whitington about coping with celebrity, how the success of her last film caught her by surprise and why she was terrified appearing on Broadway