Walsh is reunited with her longtime friend, fellow Corkonian, and Disco Pigs stage co-star Cillian Murphy in the just-released adaptation of author Claire Keegan's bestseller, the first film from Murphy's new production company, Big Things Films.
She plays Eileen, the wife of Murphy's character, Bill Furlong - and delivers a typically excellent performance.
Looking back on making Small Things Like These in New Ross, Co Wexford, Walsh said she felt the pressure as day one of filming loomed.
"This was the first time that I genuinely felt it. I feel like I've kind of gone, 'I think I'd be right for this', and then you suddenly go, 'Yeah, I hope you can bring it now!' (Inhales sharply) So, terrified."
The Tim Mielants-directed Small Things Like These has a Magdalene Laundry at the centre of its story as Murphy's character Bill reaches a crossroads in his life in December 1985.
"You can't play all that trauma, you just can't," Walsh said of honouring the women of the Magdalene Laundries and their children on screen.
"But what you can do is siphon down into, 'What does it mean to this story, this couple, this man right now?' and then if you play that right, then you get the history that follows in with it. Otherwise, you'd get drowned in the expectation."
Like co-star Murphy, real-life stories of the Magdalene Laundries have been coming to Walsh since she began working on Small Things Like These. Early in her career, she played one of the young women in Peter Mullan's 2002 film The Magdalene Sisters.
"[Recently,] I was walking my dog in London and I met this man who was the son of the woman [June Goulding] who wrote this book called The Light in the Window," she recounted.
"[She was] A midwife who wrote the story of having to work in a Magdalene [Laundry] as a midwife obviously and help the girls give birth.
"And I just thought, 'Oh my God, all the way over in Scrubs, Wormwood Scrubs (an open space in Old Oak Common, west London)... here I am and I meet the son of her'. It's amazing the amount of people that have been touched by it and are affected."
Small Things Like These is in cinemas now.
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