Emma Thompson has revealed that she was really annoyed by her Saving Mr Banks character, Pamela Lyndon Travers.
The two-time Oscar-winning actress admitted that listening to audio recordings of the Mary Poppins author in meetings to prepare for her role proved to be quite a challenge.
"It's really hard work listening to those tapes, because PL is so awful and so irritating," she said.
"Just listening to them makes you want to throw something heavy at her. But there are lots of little clues about what was really going on, as well."
Emma - who won an Oscar for her Sense And Sensibility screenplay - said that, as a writer, she understands why Pamela was reluctant to hand over the film rights to her creation to Disney.
"I'm a screenwriter so my characters are designed to move from the page to the screen, and I always find that rather thrilling. But I'm quite vicious if they're not coming round in the way that I want. She had a different journey to make," she said.
"She felt she was giving up a part of herself to be misinterpreted... She described her [Mary Poppins] as family, in the same way that Walt Disney described Mickey Mouse as family and Sylvester Stallone would describe Rocky as family.
"There are some things you just can't let go of, and she did in the end because she needed money," she added.
:: Saving Mr Banks is in cinemas now.