In an interview with GQ, John Lithgow suggests that he is truly an Englishman – and a respected performer with ties to the UK. During his early days as an actor, Lithgow attended drama school in London. The actor joked, sharing that he “speaks as English as an American actor can get.” Interestingly, Churchill also had ties to the United States – his mother, Lady Randolph Churchill, was born in New York.
“I went to drama school in London many years ago, so there’s an English story like this. I speak of English as an American actor can understand, to the point of pure. You know, when you think about Churchill, he’s different from every other Britisher like any other American. He’s a freak. They just love the idea. They say, ‘We’ve seen all the girls. played Churchill. We saw Burton do it. And Albert Finney did it. And there was a whole bunch of people that year, and they were all British.”
https://www.slashfilm.com/984391/why-the-crown-cast-an-american-in-the-role-of-winston-churchill/ Why the Crown chose an American to play Winston Churchill