Saoirse Ronan says playing Mary Stuart gave her "strength" as an actress.
The 24-year-old star plays the titular role in historical drama film 'Mary Queen of Scots' and has revealed that being asked to lead the movie by director Josie Rourke helped her in both a "personal and professional sense" as she was thrown into a world that was alien to her previously.
In an interview with the Daily Mail newspaper, she said: "Making the film was brilliant for me in a personal as well as a professional sense. I was being prepared to be thrown out into the world in a way I hadn't been before. With that comes fear. The fear of having to make decisions that hadn't really been laid on me before.
"The kind of decisions that weren't going to make that person over there happy, but one that's right for me. Honestly playing Mary gave me that strength.
"Ultimately when it came to work, I always knew what I wanted to do and what I didn't want to do. But it's very easy to say this is the thing I want to do, and hard to say this isn't what I want to do."
The central plot of the movie is the fractious relationship between Mary and her cousin Queen Elizabeth I - the ruler of England and Ireland who is played by Margot Robbie - and the 1569 conflict between their two kingdoms.
Saoirse says the dynamic and differences between her character and Margot's alter ego were fascinating to her.
The 'Lady Bird' star said: "One essentially wants anything that a man has been afforded; lovers, the ability to rule, a family, friends, being able to enjoy her life and art and music and drink and whatever else.
"And then, there's Elizabeth, who's the one who ends up having the longest reign because she cuts herself off from anything human that will get in the way."
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