Sir Kenneth Branagh's Boris Johnson transformation took three hours "a day".
The 61-year-old star looks uncannily like the former British Prime Minister in Sky's political drama 'This Sceptred Isle'.
However, it took a lot of work to get him to resemble him, with Branagh having to don a suit to bulk him up and a number of prosthetics.
He told heat magazine: "It took about three hours each day to get into a suit that bulked me up and then to wear various prosthetics.
"One was like a neck piece balaclava, and a lot of time was spent making sure the pieces were blended seamlessly into my own skin so you couldn't see the join."
One of them was a "bigger upper lip", which made it impossible for Branagh to eat.
He even had his eyes sloped like 58-year-old Boris.
Branagh added: "Then we had to pull down the eyelids to have the sort of slight slope that is a Johnsonian family trait - followed by a hairpiece, and a bigger upper lip ... it was very brilliantly done, but it was not a prosthetic that allowed you to be in a world of chewing - or consuming soup during the day."
The filmmaker decided he did not want to meet Boris - who was ousted as PM and replaced by Liz Truss - before taking on the role.
He said: "I've never met him, and I decided not to go down that route.
"The job was to try and create a physical picture of the man - and then try as best you can to recreate everything in this drama that was real, that happened on particular days at particular times.
"I did a very minute study of the way he delivered his speech when he came out of hospital, when we left Europe... and hopefully you build up a kind of vocabulary of tone that allows you to maybe get somewhere near the spirit of something truthful."