Set to release on November 5, Spencer is a biopic film focusing on Princess Diana. The film follows the story of the royal family at Sandringham House when Princess Diana decided to leave Prince Charles in 1991.

       However, Ms Stewart laid bare her British co-stars, Jack Nielen, 12, and Freddie Spry, ten, who played William and Harry, were shocked at her knowledge.

       She said: “They are so English and had deep, developed relationships with the Royal Family as an entity, and at times knew more than I did.”

       “They were like, "Well, did you know them? What actually happened was…" I was like, oh, OK!”

       The announcement of the film has stirred controversy among royal fans but Kristen Stewart has reassured fans the biopic will not present “any new information”.

       She said: “I've been asked a lot about whether or not it's cool to try and tell someone's story when they're not around and somebody who was already so sort of invaded and taken from.”

       She added: “We really don't profess to know anything or present any new information.

       “We can't stop talking about her.

       “My hope is that because we made it so personal.”

       READ MORE: Camilla viewed as a 'good thing' as popularity increases

       Diana, who married Prince Charles in 1981, welcomed sons Prince William and Prince Harry before separating from the heir apparent in 1992.

       Their divorce was made final in 1996 - just a year before her tragic death in a car crash in 1997.

       During her 15 years in the spotlight, Diana took the world by storm, earning herself the love and adoration of millions across the world.

       Kristen Stewart has also spoken about Emma Corrin’s portrayal of Princess Diana in the Netflix series The Crown.

       DON'T MISS

       Meghan Markle could get major 'rebrand' [REVEAL]

       Meghan Markle praised after book does 'very well' despite odds [INSIGHT]

       'Classy' Meghan Markle pays ￡18 to buy staff a coffee [ANALYSIS]

       She told Entertainment Weekly: “I think [actress Emma Corrin] did a really beautiful job.”

       She added: “I mean, not to say that my opinion matters at all, but I loved her in it, truly.”