"It was really exciting to play someone who was older than me," says Ronan. "For some reason when you're in your early 20s, it's a tricky time for an actor to find a character that fits where you're at when it comes to your own maturity in your own personal life and experience.
"Usually, I get asked to play teenagers who have never been kissed as they're just out of high school. That was the kind of stuff that was coming to me, romantic dramas or comedies about teenagers who were younger than me, so I really felt like I'd struck gold when I was asked to do Brooklyn."
Noting that she "did Eilis' journey in reverse," Ronan was born in the Bronx before shifting back to Ireland with her parents when she was 3. "I grew up just 20 minutes away from where Eilis grew up, in a village that actually had even less than Enniscorthy, " recalls Ronan. "The village consisted of a church, a school, a pub, a graveyard and a few houses, and that was it. And we actually lived a mile outside the village, so we didn't even live in the village itself.
"And like Enniscorthy, it was a small, tight-knit community, where everyone knew each other, which can be a good thing and sometimes a bad thing.
"So I know what it must be like to have the security and safety of knowing everyone and knowing how almost every day is going to go, as well as having the space of the countryside.
"It's a time I miss even now, but I also understand why you would want to get out of a place like that."
Directed by John Crawley from a screenplay by Nick Hornby, the film is based on Colm Toibin's bestselling 2009 novel Brooklyn, which Ronan read several years ago before being approached to play Eilis.
"Someone gave it to me, and encouraged me to read it, as it was a story that was not too different to what I'd been through," says Ronan. Unlike Eilis, who could only occasionally phone her family, Ronan is in constant communication with her mother whenever she travels abroad. "I usually speak to my mum about five times a day, whether it be FaceTiming, WhatsApping, texting or whatever," she says. "My mum is such a huge part of my everyday life, so to go away and suddenly not have her there can be unbearable
"To know that I'm always connected to her, even if it's just through a little phone, puts you at so much peace of mind. I just came back from a job, where I was away for about six weeks, and when I got home it didn't really feel like we'd been apart.
"It was like she'd been in the next room all the time, and it's incredible that technology can keep people in contact in that way, as it frees you up to travel more."
Having risen to prominence as a 13-year-old in 2007's Atonement, Ronan comes of age as an actor in Brooklyn. Already nominated in the Best Actress in a Motion Picture Drama category at this year's Golden Globes, her memorable performance has led some critics to tip her as a frontrunner for an Oscar. Labelling such accolades as "nice," she hopes that playing "an older, more mature young woman" like Eilis will lead to her being offered a wider, more adult range of roles. "I want to do more stuff like that in that age bracket," she says.
"I really want to progress as an actor but it's been a bit difficult over the past few years as I didn't just want to do anything for the sake of it. "Hanna is probably the last thing that people remember me for, and I did that when I was 15. So it's really nice to have Brooklyn now, as I can show people what I can do."
On screen
What: Saoirse Ronan in Brooklyn
When: In Cinemas on Thursday
