Taron Egerton had met Elton John during press tours for his 2017 action film Kingsman 2: The Golden Circle. But the actor didn't really get to know the music star until preparing to play him in quasi-biopic Rocketman.
Over dinner at Elton's home in London, the pair had a deep personal conversation.
"There's something about that evening that would feel slightly sacrilegious of me to share," Taron, 29, tells TV WEEK.
"But what I will say is there is commonality to some of the things Elton has found hard in his life and some of the things that have happened in mine.
"It was a hugely significant, emotional experience for me, and it was the start of a really lovely relationship with him."
Taron channelled what he learnt – and hundreds of hours of piano lessons – into a musical fantasy that highlights Elton's life from the age of six until 43, when he went into rehab for drug and alcohol addiction in 1990.
For example, Elton's teen years are illustrated at a funfair to the tune of his 1973 hit "Saturday Night's Alright (For Fighting)".
"Because it's a non-naturalistic piece, there's no chronology to the songs," Taron explains. "We've taken the songs and used them where it feels best to illustrate a certain kind of emotional beat or plot point in Elton's life."
Adding authenticity, Taron plays some piano and does all his own singing in the film. Even so, Taron says despite the bond he has with the legendary performer – who's now 72 and married with two children – his commitment to the film means daring to provide an unvarnished look at Elton's world.
"Elton was notoriously tempestuous, is notoriously polarised in his character traits, and my performance is the same," Taron says. "I was never interested in doing a sanitised, Disney-fied version.
"And, provided the edit goes the way I seriously hope it does, I think this is going to be a really exciting thing to watch."
ROCKETMAN is in cinemas May 30.