Kristen Stewart felt the weight of responsibility playing Princess Diana in 'Spencer'.

Kristen Stewart

Kristen Stewart

The 31-year-old actress portrays the late princess in the new psychological drama film, which focuses on Diana's decision to leave the Royal Family, and Kristen has admitted that she felt under pressure in the role.

She shared: "I felt I wanted to protect her. I had to just not focus on other people's idea of her, and really focus on my own. And that in itself was just so distinct and specific to me."

Kristen studied Diana's behaviour and mannerisms in preparation for the role.

And she admits that the late princess - who died in Paris in 1997, aged 36 - was "unpredictable" in many ways.

She told the BBC: "I think to do her justice is to allow her to be impulsive.

"Anything I watched her in, whether it was an interview, or even in a still photograph, it always feels unpredictable. Like you don't know what's going to happen.

"And it's because she has this vulnerability and this raw emotion that she cannot conceal. There's no way to do a perfect impression of that.

"You have to feel it, and it has to be yours. So I think I just had to relax."

The movie touches on Diana's eating disorder and struggles with her mental health.

Reflecting on the project, Kristen shared: "The movie is very surreal. I think that when you go through extreme trauma in life, there are times where you feel crazy. I never felt the implication of Diana, losing it.

"There are there are times where you are at odds with communication and therefore feel because of this muzzled energy, a bit locked in your own head.

"And she spoke about that. I mean, that was something that she talked about all the time. And so I felt to be honest, it felt truer than the truth."