Kenneth Branagh says he lost his Belfast accent within three years of moving to England in an effort to "fit in".
The 61-year-old director and actor, who is about to release his Golden Globe winning new movie Belfast, added that he had tried to keep his native accent and felt a bit guilty when it disappeared, reports entertainment website Vulture.
"It was in the two or three years after I came across. We left when I was nine, May of 1970," he said.
"And by the time I left [primary] school in the summer of '72, it was probably gone. I think it was to do with wanting to disappear. I wanted to just fit in.
"As we all became a bit more insular, [my accent] kind of rubbed off. There were a couple of years of not even knowing it was happening, then feeling a bit bad about it.
He added, "So, for a while, I was English in school and Irish at home. And then it started happening at home. My parents didn’t comment about it. I think they felt it was natural enough."
Branagh went on to star in movies such as Dunkirk and Tenet and direct numerous films, including his acclaimed semi-autobiographical Belfast, which stars Jamie Dornan, Caitriona Balfe, Ciaran Hinds and Judi Dench.
It won a Golden Globe for Best Screenplay on Sunday and was also nominated for Best Director and Best Screenplay for Branagh and Best Supporting Actor nominations for Dornan, Hinds and Balfe.
One of Branagh's earliest screen appearances was in the Billy plays, a series of BBC dramas aired in the early 80s about a working-class Belfast family.
"I went back with a friend of mine, the guy who plays the best friend - an excellent actor who’s a policeman now, called Colum Convey," Branagh recalled.
"When we got on the plane on the way to Belfast on the Sunday night before the first day of rehearsals, Colum said to me [in a Cockney accent], 'Now, listen, Ken. From tomorrow, I’m going to be completely Belfast. All right?’
"And that’s what he did. The next day, it was like meeting a completely different guy.
"Whereas I didn’t feel comfortable with that. I had the mickey taken out of me left, right, and centre, but I would do the part and then I would step back into the way I sounded.
"I’ve never been good at doing that totally immersive thing."
Belfast is in Irish cinemas later in January.