Rhys Ifans was stunned to learn his NANNY MCPHEE AND THE BIG BANG co-star Maggie Gyllenhaal was American - because she had such a convincing English accent.
The actress, who plays a busy mum in Emma Thompson's new family movie, worked hard to master her speech for the role - and even managed to convince Ifans she was from the U.K.
He tells Britain's Live From Studio Five, "It was amazing. I didn't realise she was a Yank until about three weeks in. She kept it going the whole time, even in the make-up trailer, this pristine period English accent.
"I almost wanted to spill hot coffee on her to see what it would take to get this girl to do (an) American (voice). She was that good."