Oldman reveals that one way in which he developed Oldman’s voice is by treating it like learning music. He explains:

“Churchill had a very distinctive cadence, more so when he spoke publicly. His range is a little lower and fuller than my own. I worked with a man, a singing teacher, and an opera singer, Michael Dean. We had a few sessions on the piano and we worked out the range of Churchill on the keyboard. With exercises and working with him and the recordings, you find what lower notes I needed to hit. Churchill would work until three or four in the morning and he wrote to his wife in 1924, he said ‘I like champagne at every meal and plenty of claret and soda, in between.’ You would hear these recordings and you could always tell if he had had a few brandies because you could hear it. That was challenging, getting that whiskey cigar sound. You are playing arguably the greatest Briton that ever lived for starters. But you are also playing an iconic character whose silhouette, the shape he makes, his face is very iconic. What we think we remember, he doesn’t really sound like that.”

(via)