Michael Sheen has never met British Prime Minister Tony Blair, yet he’s intimately familiar with Blair’s physical mannerisms, speech patterns, and details of his private life.

Sheen isn’t an obsessed fan. He’s an actor who plays Blair in The Queen, a new film about the controversial response of both Blair and Queen Elizabeth II in the aftermath of Princess Diana’s death in a 1997 auto accident.

For Sheen, the role was familiar. He previously played a younger Blair in The Deal, an acclaimed British television movie a few years back about Blair’s beginnings as a politician and his struggle to become leader of the country’s labor party.

Both films were directed by Stephen Frears (Dangerous Liaisons) and written by Peter Morgan (The Last King of Scotland), so his casting the second time around seemed to be a no-brainer. But Sheen said preparing for the follow-up portrayal still was a challenge.

“By the beginning of The Queen, he’s very different, I think, than he was at the end of The Deal,” Sheen said during a recent promotional stop in Dallas. “There’s still a freshness and youthful exuberance about him that made him appealing to the voters. On the one hand, he’s more relaxed because he’s where he wanted to be. But on the other hand, his work is only just beginning. He has certainly matured as a man.”

The film finds Blair, only months into his tenure as England’s top elected official, becoming a sort of mediator between the stubborn queen (Helen Mirren), who is eager to distance herself from the daughter-in-law she never much cared for, and the British people who adored Diana, engulfed Buckingham Palace with sympathy flowers, and demanded a public funeral.

Sheen, 37, said he shared a certain apprehension with Mirren about playing real-life public figures who are recognizable worldwide, and who are still alive, to boot. To prepare for the role, he immersed himself in research during the weeks leading up to filming.

“No matter what you’ve done before, to play someone who’s so well known is really scary,” said Sheen, adding the idea is “not to try and copy them. You’re trying to look for something that just gives you a little clue about what makes them tick inside and why they make the choices they make. You do all the work beforehand, and then just react.”

The Queen has been well received during its theatrical rollout in the United States this month. But Sheen has been more impressed with its favorable response this fall among British audiences, whose connection to the story is much more personal.

“We thought for sure, even if the film was a success, that it would divide people,” Sheen said. “Everyone has a different opinion about Blair and about Diana — there’s so many pitfalls there. But they’ve all gotten completely behind the film. This is a film about us — about our country and about a very important event in our culture.”

Sheen said he hopes the film’s balance of humor and poignancy, in the face of national tragedy, helps to make some of England’s most powerful and well-known public figures less emotionally remote and more identifiable with the general public.

“Any of the humor in it, and the cheekiness of it, only serves to make you empathize more with the characters,” he said. “It never serves to belittle anyone. They’re always real human beings. What we’ve managed to do is to put them in a context to make it more understandable why they are the way they are.”