'Darkest Hour' star Gary Oldman on his remarkable transformation into Churchill

— -- British actor Gary Oldman has played so many different characters in so many films that ABC's film critic Peter Travers believes he's the chameleon of chameleons. But it’s his role as Winston Churchill in the new film “Darkest Hour” that has finally grabbed the attention of his children.

“My kids have been really underwhelmed. Most of [my] work they haven’t seen,” Oldman said in an interview on “Popcorn With Peter Travers.”

But this time it's different. He’s finally impressed one of his older sons.

"For the first time, my young Charlie, who is 18, said, ‘Wow, that was a really good performance. Wow, that’s a great movie.'"

Oldman is nearly unrecognizable as Winston Churchill and he talked about his dramatic physical transformation.

“It took three hours, 15 minutes and then getting into the costume and everything, it was just under four hours, 48 days consecutively," Oldman, 59, told Travers. "And then I would be dressed as Winston by the time the director arrived and the other actors for rehearsal. So it was very odd. They did not see me as Gary for three months for the entire shooting because I was always in my makeup.”

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And taking off the makeup was almost as long as putting it on.

“It's a very slow sort of process where they have a solution that melts the thing and so really by the time I had hit the pillow at night it was about an 18-hour day. And I worried that I would not have the stamina to get me through it. But I loved every minute of it,” he said.

When Travers asked Oldman if he felt intimidated that other actors have recently played the same character, Oldman said he found inspiration in old news footage of Churchill.

“When I went to the Pathe’ newsreel footage of Winston, and this was particularly early on in the war, there was an energy and a vitality to him, cherubic face with a real sparkle in his eyes. And he had this sort of little grin on his lips. And he was marching out ahead of everyone. He was like just this man on this mission. And it was vital and dynamic.”

He added, “It was a chance to show a different side of (him), a different energy.”

"Darkest Hour" is in theaters everywhere.

Be sure to watch the full interview with Peter Travers and Gary Oldman in the video above.