The British actress was a relative unknown before landing the prestigious role in the fourth season of the Netflix drama. However, casting director Robert Sterne has revealed that she was actually involved in the programme in a different capacity at first.
Explaining that Emma was acting as a reader opposite the actresses auditioning for the role of Camilla Parker-Bowles in the show, Sterne told Elle magazine, "I usually read in all these meetings, but we decided because it was this major scene that we would get somebody to come in (for Diana)."
"We asked Emma to come in, not thinking about casting Diana at this point. But as she was reading with these Camillas, all the directors and the showrunner were looking more at her and not at the people playing Camilla - who will remain nameless, of course. When we got to thinking about Diana a year later, there she was in my notes."
Emma was later cast as Diana opposite Josh O'Connor as Prince Charles while Emerald Fennell landed the part of Camilla.
The fourth season of "The Crown" caused big reactions as it focused on the relationship between Princess Diana, then-husband Prince Charles, and his lover Camilla.
The heir apparent to the British throne and his now-wife Camilla were forced to shut off the comment sections on their Twitter and Instagram due to backlash from Diana's supporters.
British minister even asked Netflix to add a disclaimer warning fans that the show was a fiction, but the streaming service refused. Instead, the company promoted a documentary called "Diana: In Her Own Words" amid the controversy.