The actress has received high praise for her performance following the movie's premiere
Last weekend, 'Spencer' had its world premiere at the Venice International Film Festival.
The feature sees Kristen Stewart play the role of Diana, Princess of Wales (née Spencer).
Early reviews of the movie have seen Stewart earn high praise for her performance, and many believe she'll earn her first Oscar nomination for her turn as Diana.
'Spencer' is directed by Pablo Larraín, who is best known for directing 'Jackie', starring Natalie Portman.
The biographical drama depicts the breakdown of Diana's marriage to Charles, Prince of Wales (played by Jack Farthing), and her decision to leave the Royal family.
In an interview with the LA Times, Kristen Stewart opened up about the challenges of playing the icon.
The actress described Diana Spencer as "such a live wire", continuing: "Any picture or interview I’ve ever seen of her, there’s an explosive, ground-shaking quality to her that I always feel like you never really know what’s going to happen.
"... She just has this feral cat feel. So I wanted to convey that. There’s no way to plan chaos. You just have to fall into it."
She spoke of being able to relate to her: "I know what it’s like to feel backed into a corner. I know what it’s like to feel defiance, and then kind of regretful of that, because then suddenly, you are being defined as rebellious.
"... It’s a convoluted idea, but I definitely understand what it feels like to want human connection and actually, ironically, feel distanced by the amount that’s thrust at you."
She also spoke of "feeling at home" making the movie, saying "there's an energy that's unrelenting."
She describes: "I had so much fun. I felt like I was allowed to and encouraged to be a leader, because she was. It just felt like she had this effortless figurehead kind of feel. Diana just felt like everyone wanted to go with her. She’s, like, the best kindergarten teacher you could ever imagine."
Kristen Stewart also mourned Diana Spencer as she made the movie.
She says: "She felt so alive to me when I was making this movie, even if it’s all between the ears and it was just a fantasy of mine. But there were moments where my body and mind would forget she was dead. And suddenly, I would just have an image of what happened, and remember who she left behind.
"And I was amazed by the renewed emotion. Every single time. Maybe two or three times a week, I would just fully break down about the fact that she had died. I just could not come to terms with it, because I was fighting to keep her alive every single day."
The Irish release date for 'Spencer' is TBC.