Film stars frequently rise to their place in the showbusiness firmament trailing a glittering series of lead roles and fiery celebrity feuds behind them. Others, like Saoirse Ronan, appear there suddenly, twinkling down benignly.

The Golden Globe-winner, now an A-list performer despite being only 23, is the open-faced, unpretentious Irish-American actor whose starring role in the acclaimed new film Lady Bird, along with forthcoming lead parts in the films Mary Queen of Scots, On Chesil Beach and The Seagull, is about to heavily underline her arrival in the first rank of talent. Yet reaching the top of the casting directors’ wishlists has been quietly achieved, through a succession of carefully delineated roles in unusual and complex films, such as Brooklyn, The Grand Budapest Hotel and Atonement.

Ronan’s latest performance, as the bolshy Sacramento teenager known as Lady Bird, has earned her awards and nominations in abundance. According to the New York Times, she plays the part, which is loosely based on the young life of the writer and director Greta Gerwig, “with daunting, dauntless precision”. She is already, the newspaper suggests, one of “the most formidable screen actors” of the day.

Fellow stars are also impressed. “Saoirse doesn’t have a dishonest bone in her body and that translates directly into her work, on to the screen,” Colin Farrell has said.

And as if all this early exposure and praise for her film work isn’t enough, Ronan also took to the Broadway stage with aplomb a year and a half ago as Abigail Williams in Arthur Miller’s The Crucible. She was “the face of this production” as far as the Hollywood Reporter was concerned, “icy and commanding in her first stage appearance”. What’s more, Ronan turned up last year in Ed Sheeran’s video for his hit song Galway Girl. With the exception of this little pop outing (and perhaps her cameo in Muppets: Most Wanted) the actor is distinguished by a succession of rather sober career choices. She has taken risks with sophisticated screenplays, instead of opting for obvious crowdpleasers.

The fate of Lady Bird has become something of a Hollywood cause célèbre, although it is still a month before the film is released in Britain. As the teenager who insists her given name is Lady Bird – in the sense that she gave it to herself – Ronan is carrying much of the weight of this female-centred drama at a moment when such factors are especially significant. So when the film was ignored in the best director category at last Sunday’s Golden Globes ceremony many sculpted eyebrows were raised, especially as it went on to win as best film, while Ronan won as best actor. Awards presenter Natalie Portman spoke for many of those clad in black that night when she queried the line-up of male nominees. Things have been set straight since with a Director’s Guild of America nomination for Gerwig, although only Ronan was recognised in the Bafta line-up.

Accepting her shining gong last week, Ronan mentioned that her mother was not with her for the ceremony, but was watching on Facetime. This prompted the Irish press to find out why. She was, it has been revealed, staying at home to mind a new puppy, Fran. It might sound odd to miss such a family triumph, but then Mrs Ronan has not been short of reasons to be proud.

Her daughter, who was born in the Bronx in New York City, has already been widely nominated for awards during her short career: first at the age of 13 for her fateful role as Briony Tallis in the 2007 film of Ian McEwan’s Atonement and then as the luminously reserved Irish immigrant, Eilis, in Brooklyn, adapted from Colm Toíbín’s novel in 2015.

Ronan in Joe Wright’s film version of Atonement, for which she was nominated for an Oscar. Photograph: Shutterstock

In fact, her own parents’ story is not so far removed from the transatlantic questing in that story, although Paul and Monica Ronan’s attempts to make a new life away from Ireland belong to a later era. Her father worked on building sites and then behind a bar, while her mother took a job as a nanny. After trying out as an actor, her father went on to work on a series of films, appearing with Brad Pitt in The Devil’s Own. But his daughter now claims family memories of that tough time are sobering when Tinseltown threatens to dazzle.

“They had to struggle for a long time,” she has said. “Ma watched dad lose out on parts or star in shows off-off-Broadway and make buttons. She watched these really talented people never get the shot they deserved,” she has said. “So they prepared me to be realistic. And that’s good, because the moment fame becomes a priority, you should give it up.”

The young family eventually moved back to Co Carlow in Ireland, which accounts for Ronan’s lilting Irish brogue. Early on, she won a role in an Irish soap show called The Clinic, and going to school soon became problematic. Neither of Ronan’s parents had enjoyed the academic life. Monica had left school at 15 after “trouble with the nuns” and her father had not done much better. So when Ronan began to feel that her teachers and fellow pupils were “giving her a hard time”, she opted for home schooling instead.

“Some of the students were, you know, mean. But when your schoolmates recognise you before they’ve met you, and the teachers do too, it can make things very awkward and difficult,” she has said.

Her big break came with Atonement, a part she secured because she had worked with the dialect coach involved on the film on another aborted film project. By dint of her skill, Ronan was cast against type as Keira Knightley’s little sister. “Briony was supposed to be this brown-haired, brown-eyed, middle-class English girl – she was supposed to look like she was related to Keira,” says Ronan, gesturing to her pale skin, freckles and blond hair.

Although Briony is the catalyst for all the pain in the story, Ronan has always staunchly defended her. “People say Briony’s a bitch, and she’s not. She’s not vindictive or spiteful. It’s just that she doesn’t express her emotions; she just sits and observes everything.”

This relationship with McEwan’s fictional characters will continue this year with the release of On Chesil Beach, in which she plays his troubled honeymooner, Florence.

In the recent screen adaptation of Brooklyn, for which she was nominated for a Golden Globe. Photograph: Kerry Brown/AP

Ronan’s career understandably took off after Atonement, which had earned her an Oscar nomination, with a leading role in the 2009 adaptation of Alice Sebold’s dark bestseller The Lovely Bones, directed by Peter Jackson, and an outing as a vampire in Neil Jordan’s 2013 horror film Byzantium. Jordan, best known for making Mona Lisa and The Crying Game, responded in particular to Ronan’s “stillness”. “When she begins to act she is so totally possessed that it’s quite spooky,” he said then. “People say that some actors are naturals. Well, with Saoirse, it almost feels unnatural.”

“A certain amount of technicality comes into it,” she says. “It’s about understanding the camera: how it works, what it will pick up. It all goes very quiet on set. You can feel the atmosphere when everyone knows how important the shot is. The camera’s like a friend, sitting down, that’s just all ears, and wants you to pour your heart out. It stares – that’s its way of listening.”

With growing fame in America and Britain came a continuing struggle for Ronan: that of getting people to pronounce her name correctly. She has learned, she says, to respond obligingly to a wide variety of sounds beginning with “S”. Even the poster for the Golden Globes a few years ago spelled her name Sarise by mistake. “You actually say it Sairsha,” she has explained. “But you can also say it Sersha, or Seersha.”

She will be swapping Irish roots for Scottish with the release of Mary Queen of Scots later this year. The film, based on John Guy’s study of Queen Elizabeth I’s ill-fated cousin, is directed by Josie Rourke, artistic director of the Donmar Warehouse, who announced her departure from the job last week. Margot Robbie will play the queen, and Ronan will play Mary Stuart, who had to endure the eyes of the world on her at a tender age.

If there is one star who has had to learn to perfect teenage composure in the face of early public scrutiny, it is Ronan. It is only adopting the airs and graces of regal authority that will require a bit of imagination in this role.

THE STORY SO FAR

Born 12 April 1994 in the Bronx, New York City, the only child of Irish parents. Her family moved to Dublin when she was three.

Her breakthrough performance was playing the teenager Briony Tallis in Atonement (2007), earning her an Oscar nomination for best supporting actress. She has also starred in The Grand Budapest Hotel (2014), Brooklyn (2015) and Lady Bird (2017), for which she won the Golden Globe for best actress in a comedy or musical.