Newlywed Saoirse Ronan may not be a mum in real life yet, but she drew on the close bond she enjoys with her own mother to play a maternal figure in her latest role, in Sir Steve McQueen's big-screen wartime drama Blitz.
As a single parent in 1940s London, Saoirse's character Rita will do anything to protect her nine-year-old son George, and is broken-hearted when she feels forced to send him to the countryside with other Second World War child evacuees.
It wasn't hard for the 30-year-old Irish actress to portray the closeness between a young mum and her son.
"It's exactly in the way a young parent does with their kids, you know?" she says, speaking from Los Angeles.
"I mean, my mam had me when she was 30, so she wasn't super-young, but there's an element to our relationship that is almost like we're sisters," she says of her mother Monica Brennan, whom she has credited for accompanying her on film sets as a teenager, protecting her from uncomfortable situations.
The New York-born former child actress, who moved to Dublin when she was three years old, remains very close to her parents, having lived at home with them until she was 19.
In her own life, she looks to emulate her parents' happy marriage, having been with Scottish actor Jack Lowden since they met on the set of Mary Queen of Scots six years ago. The couple reportedly tied the knot in a private ceremony in Edinburgh in July.
Mother's love
The most important thing to get right was to convincingly portray the anguish of a mother torn from her son. It was something she keenly discussed with Sir Steve.
"We spoke a lot about our own mothers and how much of an impact it had on us, and how formative my relationship was in particular with my mother, and that really set the tone for who George and Rita were as a pair," says Saoirse, who also stars in new Scottish drama The Outrun, which she co-produced with husband Jack.
The couple – both enjoying flourishing careers, with Jack starring in hit TV spy series Slow Horses – divide their time between London, Scotland and Ireland.
In fact, their London home is close to areas bombed by Nazi Germany in a brutal eight-month aerial campaign.
"What's so mad is that I live in north-east London, and Shoreditch Park is around there, and I walk my dog there all the time. Shoreditch Park used to have rows and rows of homes all along there, and it was wiped out," Saoirse says.
"And there's now all of us actors going around with our dogs being like... there's a dog in the park called Macchiato. 'Macchiato! Come over!'
"So, this park had lives and families and histories and cultures, and it was all just wiped out. And it's amazing to go back to the city now and realise how the echo of that particular time in the war is still so present."
To read the full exclusive interview, pick up the latest issue of HELLO! on sale in the UK on Monday. You can subscribe to HELLO! to get the magazine delivered free to your door every week or purchase the digital edition online via our Apple or Google apps.