As for O'Connor, taking on a role that portrays the Prince of Wales—and heir to the throne—negatively throughout his marriage, as he continues his affair with Camilla Parker Bowles and often speaks to his unhappiness with Diana, the experience was about finding sympathy with the "troubled" royal.
"My job in season three was to help people understand where this all comes from," O'Connor tells marie claire. "I mean, ultimately, in many ways, it's a kind of unbiased telling. I think it was always going to be difficult—Diana was this icon that people loved. And there's nothing I can do, or any of us really can do, to change that public opinion.
"And so Charles is on the back foot from the onset in that sense, which is why it's fortunate that I had a bit of time in season three to maybe win some people over a little bit. But regardless, he's deeply troubled, and he behaves really badly at times."
The actor adds that while the series may depict Charles during this problematic period of his life, none of us really know what happened.
"Of course, as always, you have to acknowledge that, in reality, who knows what Charles is like? And it may well have been completely different. This is just our portrayal and narrative," he says.
It's not just the dramatic retelling that has fans excited for the series fourth instalment, but the recreation of one of the most stylish women in history. Diana's legacy as a style icon hasn't wavered since her tragic passing in 1997, and her looks are still widely used as sartorial inspiration today.
For Corrin though, despite being dressed in some of the royal's most memorable outfits—from her wedding gown to those two-piece sets—it was the young Diana's baggy statement jumpers that made her feel most authentic as the character.
"I loved what I wore when I was young Diana, she had some incredible jumpers. Some of which were replicas, or we got some exactly the same," Corrin says.
The Crown costumers even looked to the Victoria and Albert Museum's Treasures of the Royal Courts collection for some of Diana's wardrobe.
"Wearing that was wonderful because it felt like it was hers."
The Crown is streaming on Netflix from November 15.
