To say that Gary Oldman looks the part for his role in new Winston Churchill biopic 'Darkest Hour' is something of an understatement - but the actor has revealed the lengths he went to to nail Churchill's character, too.

Primarily, that involved getting nicotine poisoning for smoking too many cigars - $20,000 worth of the film's $30 million budget, to be exact - on set over a short period of time.

Oldman told The Hollywood Reporter that he smoked an insane 400 cigars over the course of 48 hours on set. “I got serious nicotine poisoning," he said. "You’d have a cigar that was three-quarters smoked and you’d light it up, and then over the course of a couple of takes, it would go down, and then the prop man would replenish me with a new cigar — we were doing that for 10 or 12 takes a scene.”

Director Joe Wright, on the other hand, claimed it was worth it, saying: "It's Winston Churchill. You can't have Winston Churchill without a cigar."

Darkest Hour hits Irish cinemas on January 12th.