During a "Variety Studio: Actors on Actors" interview with "Bridgerton" star Rege-Jean Page, Emma revealed she wasn't in consideration for the royal role, for which she has won a number of awards, when she was asked by casting directors Nina Gold and Rob Sterne to help them at readings.
"I was sort of working, jobbing, trying to earn money in London... when I got asked by Nina Gold and Rob Sterne... to come in and help for some of the chemistry reads they were doing between Camillas, who they were auditioning," she recalled.
"[Creator] Peter [Morgan] had written some preliminary scenes with Camilla and Diana, and so they needed someone to read for Diana. So I was like, 'OK'. It wasn't an audition," she went on sharing. "I was being paid to be there and I wasn't going to be on camera."
"My agent was like, 'It's the perfect situation because it's going to be a no-pressure audition'. We decided that I would just prepare as if it was an audition. And so I did and I worked on the voice with my mum, who is a speech therapist," she added. "And then I learned the lines. And I just had fun, because I wasn't really doing anything at the time."
Speaking about her preparation to portray Diana, Emma told Rege-Jean, "When I got the scripts, I could really just work off what was on the page. It's sort of a love story. It's a marriage. It's two humans navigating extraordinary circumstances by virtue of their position in society." She added, "As soon as I narrowed it down to that, I could make any research much more specific."