Colin Firth announced he has become an Italian citizen due to "uncertainty" in the world following the Brexit vote.
The film star is known for playing buttoned up British characters including Bridget Jones' Mark Darcy, Love Actually's Jamie, and King George VI in The King's Speech.
He is embracing his European side as he takes up the second passport - but pledged he would remain "extremely British".
The actor's wife of 20 years, Livia Giuggioli, is Italian and their two children hold dual citizenship.
"My wife and I are both extremely proud of our own countries. We feel that we've made a gift of that to each other," he said in a statement.
"I will always be extremely British (you only have to look at or listen to me).
"Britain is our home and we love it here."
Firth's two sons were both born in Rome but the family live in London - something he said will not change.
He was reported to have applied for Italian citizenship in May.
"Our children have been dual citizens since the beginning. We never really thought much about our different passports," he said.
"But now, with some of the uncertainty around, we thought it sensible that we should all get the same."
He added: "Like almost everybody I have a passionate love of Italy and joining my wife and kids in being dual citizens will be a huge privilege."