Olivia Colman has said that working on Locke was a very different experience because she never actually appears on screen.
The Broadchurch star's voice features in the tense thriller starring Tom Hardy as a construction manager who gets a series of life-changing phone calls as he drives from Birmingham to London in real time.
Asked what it was like to voice one of the characters who calls him, Olivia replied: "Quite difficult, I suppose what we were doing was a radio play really and he was doing film so we were trying to get them to tie in.
"But it was lovely, because you didn't have to wear any make-up, and it was all done on night shoots so we were kind of in slippers and it was very nice."
Describing how it worked, she said: "We were all in a holding room and we ran the whole thing as a play so we kept running it and we called in. We didn't want to be late for poor Tom as he was driving around.
"He knew the story but we were told slightly different ways of doing it each time, so he had to react."
Rev actress Olivia is also starring in the upcoming film The Lobster, a love story set in the future where single people are arrested and forced to find a partner or be turned into an animal.
She said: "It's very disturbing. I quite like dark pieces and it's quite dark and quite weird."