(LONDON) -- Stepping into Princess Diana's shoes on the 15th anniversary of her death can't be easy.
"It's very scary and I kind of wanted to say no but I couldn't," actress Naomi Watts told the Press Association this past February, after she accepted the role of the princess in the first big-screen biopic of Diana's life.
Not only is the actress Diana's doppelganger, as pictures from the forthcoming movie show, but her co-star Naveen Andrews is convinced Watts was the only one who could play her.
"I don't think anyone else could have done it," the former Lost star told the Press Association. "There's no one else."
In fact, there have been several other actresses who have played Diana before and after her death, including Catherine Oxenberg, a distant cousin of the British royal family. But all the previous portrayals have been for television.
Diana, which was initially titled Caught in Flight, will focus on Princess Diana's final two years, including her relationship with Dodi Fayed -- who was killed along with her in the Paris car crash Aug. 31, 1997 -- and her little-documented affair with Dr. Hasnat Khan, played by Andrews.
According to a press release from the film's producers Ecosse, the story will show how finding true personal happiness for the first time, Diana was able to evolve into an international humanitarian.
The role of the princess was initially earmarked for Jessica Chastain before Watts was cast.
Watts, who was born in Britian before moving to Australia at age 14, dived into the role.
"I'm doing all the research and there is so much to read, I just hope we make a good film and people can learn something new about her that's interesting. There are a lot of people that knew her and a lot of books to read and so much information and one story is different to the next, so it's hard to gauge what was the truth. It's going to be a tough one, it's a big beast to take on, I just try to do my best," she told the Press Association in February.
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