Not only did she watch the documentary Diana: In Her Own Words "about a hundred times", but she also met up with Diana's former secretary Patrick Jephson for advice.
But while getting the look right was one thing, getting Di's accent down pat was a matter of finding the specific words that epitomised her voice.
And now Corrin has revealed that hers was a simple 'alright'.
"I just love her voice so much. I really miss it. She goes down at the of everything she says, which makes everything she says sound quite sad," she said.
But with the pandemic causing filming to stop abruptly, Corrin reflects on her sudden 'goodbye' to the role.
“It was strange because we didn’t have any closure because of COVID. I was filming one day to the next and then I was in lockdown,” the 24-year-old said.
“In terms of someone else taking over, my friend put it really well the other day. She said it must feel like your ex is moving on, which is exactly what it feels like. It’s like, ‘Oh that’s nice, I hope they’re happy.’ But you do have to let go I guess."
Watch her nail Diana's iconic accent below.