Colin Firth has revealed that he became physically ill from his role in The King's Speech.
The actor - who plays the title role of a king with a serious speech impediment - told the Los Angeles Times that his intense connection with the character left him experiencing other symptoms after the cameras stopped rolling.
"At the end of some days on set I would get headaches, and a few times I did something weird to the nerves in my left arm and couldn't move it. I still don't know what it was," he explained.
"It sounds like an actor trying to talk about the rigours of the role, but it really was the strangest thing."
The King's Speech opens November 26 in the US and on January 7, 2011 in the UK.