Barry Keoghan has said he drew on his relationship with his own father for his role in Peaky Blinders: The Immortal Man.
The Dublin-born actor has been outspoken about his childhood, which saw him and his brother sent to different foster homes as their mother struggled, and later died, from drug addiction.
The new Netflix film is a spin-off from the award-winning TV series, which ended in 2022.
It stars Keoghan as the son abandoned by the main character, Tommy Shelby, played by Cillian Murphy.
The 33-year-old told a press conference the "absent" relationship between his character, Erasmus 'Duke' Shelby, and his on-screen father reminded him of his relationship with his real father.
Watch: Barry Keoghan tells David McCullagh about Peaky Blinders: The Immortal Man on RTÉ Radio 1
Keoghan said: "It's a real thing, stepping in to play Tommy Shelby's son. Being a big fan of the show and big fan of Cillian, I wanted to be part of it and get my teeth into it.
"It was the relationship, for me, and it was the absence I leaned into, and the experience I have in some similar ways to my absence of my dad, and the echoes I've heard of him and the kind of figure I've made him to be.
"I felt that was... a humanity. It sort of humanises Duke for me to show those vulnerabilities.
"Obviously, the kid's going to be an absolute livewire and violent and they're all reactions, they're all cries for help - not to justify each and every one."
The film follows Tommy (Murphy) as he is driven back from his self-imposed exile amid the chaos of the Second World War, where he finds Duke (Keoghan) leading violent crime gang the Peaky Blinders.
Keoghan continued: "At the end of the day, there's an animalistic thing of the cub looking for its dad.
"That's what I brought it back to when [Tommy] is finally there. This behaviour he does when he's not there, emulating him and trying to be like him from what he's heard, and trying to put it on to when he is with him.
"I wanted to lean into that, make that a conscious thing."
The BAFTA-winning actor is a new addition to Peaky Blinders and said "it was mad" to join a franchise that is "just iconic".
He added: "It is nerve-racking, it is exciting and... there's sort of anticipation to it. But yeah, it was such an experience."
The TV drama following Birmingham-based crime family the Shelbys was launched on the BBC in 2013 and ran for six series over almost a decade.
Peaky Blinders: The Immortal Man will be available on Netflix from Friday, 20 March and is in cinemas now.
Source: Press Association
