'The Crown' 's Vanessa Kirby Reveals She's in Mourning Over Leaving the Role of Princess Margaret

The actress will next be seen alongside Tom Cruise in Mission: Impossible – Fallout

Vanessa Kirby admits leaving behind the role of young Princess Margaret in the hit Netflix series, The Crown, hasn’t been easy.

“Oh my God, I’m in full grieving process,” the actress tells PEOPLE about the end of her scene-stealing portrayal of Queen Elizabeth II’s rebellious younger sister Princess Margaret.

The star is saying goodbye to the role as the series jumps forward in time for the third season. Helena Bonham Carter has joined the cast as the older Margaret.

“I just enjoyed how colorful and vivid she was,” adds Kirby, 30, who won a BAFTA for the part in May. “She wanted to identify as a princess more than any of them and also run away from that. I like how universal that sort of inner conflict is. Who I am? How do I find myself in the world I’ve been born into?”

Kirby acknowledges she had some initial hesitation over signing on to do the series “because it was just scary to take on somebody who was so well-known and she wasn’t here anymore,” says the actress of Margaret, who died at age 71 in 2002.

“I certainly felt an obligation to do her justice. Luckily we were all in the same boat, which really helped, that we were all going down together if the ship sank.”

RELATED ARTICLE: Inside Princess Margaret’s Doomed Love Affair with Peter Townsend

After reading biographies and putting photos of Margaret all over her flat in London for inspiration, the actress says the role ultimately had a tremendous impact on her life.

“I just feel so lucky,” she says. “She was so unapologetically herself, which was amazing because it really made me appreciate the need to be who you are without worrying what other people think and to try and discover it despite circumstances or obstacles.”

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As for the royal family, “I got to see them as I never had before because I felt like I lost a lot of my prejudices about them,” says the actress, who will next be seen in her first blockbuster film alongside Tom Cruise in Mission: Impossible – Fallout. “Before, I couldn’t really identify with them but I got to know them as human beings and that was a really amazing thing.”

While Kirby was working and unable to watch Harry and Megan’s wedding as it happened, she found it to be “amazing,” she adds. “Because Harry gets to choose who he wants to marry. She’s divorced and he got to marry her. As a ‘Team Margaret’ girl, I felt really proud and glad that things have changed so much and people are able to be with the people they really love.”