Naomi Watts says that playing a real-life character comes with extra pressure and responsibility.
The Oscar nominated actress returns to the big screen this week as she plays Princess Diana in new biopic Diana; which sees her work with director Oliver Hirschbiegel for the first time.
And Watts revealed that she had to change the method in which she created the character because she was playing a real person.
Speaking at the London press conference for the film the actress said: "When you play real-life characters, there is always an extra sense of pressure because of responsibility to tell the story in the most truthful and accurate way.
"With Princess Diana, there is no one as well known as her to date, she is so well documented.
"I found it incredibly difficult in the preparation as well, because when you are creating a character, you start from the inside. You create the interior life and then work out; so the way that they look and speak comes last.
"Of course, I had to work in the opposite direction for this, and that took a lot of preparation and study."
It has been a busy year for Watts as she has enjoyed huge critical success with The Impossible, as well as completing other film projects.
She is set to star in St Vincent De Van Nuys and Birdman; the latter seeing her work with director Alejandro González Iñárritu.
Diana is out now.
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