Jake Gyllenhaal spoke exclusively in a British accent while shooting his latest film.

The 29-year-old actor plays the lead in upcoming action movie Prince of Persia: The Sands of Time. He had to put on an English accent for the role, and was so keen to give his best performance, he stayed in character from the day shooting began to the day it ended.

“Jake would chat with crew and visitors in a British accent,” a film set source said. “It was funny to hear this American guy talking in an accent when he wasn’t shooting. He took it very seriously.”

Jake bulked up for the film, following a strict diet and exercise regime to make sure he looked good in his skimpy costume. He was so thrilled with the way his torso looked, he spent most of his time walking around with his shirt off.

“It’s a very physical role. He was very proud of the way his body looked. He was constantly shirtless,” the source added.