Real monarchs may derive their authority from a higher power, but on the set of The Crown, queens are anointed by casting director Robert Sterne. 

The series’ six seasons span more than 50 years of Queen Elizabeth II’s life and reign, and throughout, Sterne has been tasked with finding the right actors to bring creator Peter Morgan’s vision to life — not once, not twice, but three times. In a surprising twist, The Crown recast its leads every two seasons, an unprecedented ask that Sterne says drew him to the project from the beginning. “It was a unique challenge,” he tells Tudum. “[I’ve] never done a job where you had to do it again in two years’ time, and it was daunting.”

Sterne worked alongside legendary casting director Nina Gold to find talent for the first three seasons before taking over for Seasons 4 through 6. Over the years, he’s perfected the art of blending veteran and prestige talent with memorable new faces: In Season 4, he led the search for the unique performer able to embody Princess Diana during her early courtship with Prince Charles, eventually landing on newcomer Emma Corrin, who then passed the torch to Elizabeth Debicki in Season 5. The final season sees the screen debut of Ed McVey, Meg Bellamy, and Luther Ford in the roles of Prince William, Kate Middleton, and Prince Harry as they come of age in the early aughts. The series finale brings together all three versions of Queen Elizabeth for a dramatic and emotional sequence. “I love that episode,” he says. “To see them interact is amazing.”

As The Crown takes its final bow, Sterne is sad to say goodbye, but proud of what he’s accomplished. “We said we were going to do six [seasons], and we’ve done it,” he says. Ahead, he gives a sneak peek at how he pulled it all off. 

Matt Smith as Prince Philip in The Crown, Season 2.

Robert Viglasky/Netflix

Jonathan Pryce as Prince Philip in The Crown, Season 5.

Alex Bailey/Netflix

Why did The Crown recast its main characters every two seasons? 

“We knew that if we were going to [film] over those periods of time, we didn’t want to have those original actors in just increasing layers of makeup. People are different people at different times in their life. So, Matt Smith played the strutting alpha male version of [Prince Philip], which Tobias Menzies [also] has with a bit of steel, but then has his midlife breakdown, and then you get Jonathan Pryce who’s got this alpha male thing, plus all this amazing soulfulness as well. The combination of those three people playing that role gives so much more than if you just had one actor playing in makeup all the way through.”

How do you cast characters based on real people?

“We really encourage the actors not to do impersonations — people trying to get too quickly to the point where they are physically like the character, or doing mannerisms  — because it becomes a bit two-dimensional, and it means that you are making judgements about the characters before you’ve even started working with the other actors and on the scripts. When they’ve got the part, they can work with all these amazing voice and movement teams and work it out and construct it properly [later]. But for the casting of it, you want somebody who’s going to be open to having a discussion about how they feel that person really is. It’s about getting a connection going with that character.”

What was the most unexpected casting decision in the series?

“When Erin Doherty came in and played Princess Anne, I didn’t see that one coming. She’s nothing like [her in real life]. I’d seen her in a play, and she was really brilliant and transformed herself. She came in and she said, ‘I know this woman. I’ve been watching YouTube videos of her for hours. I love her and I know who she is.’ And then she just did it. She didn’t do an impersonation. She just found a way in that was funny and moving.”

Claire Foy as Queen Elizabeth in The Crown, Season 2.

Robert Viglasky/Netflix

Was Claire Foy always going to play Queen Elizabeth?

“When we first started, there was just this amazing script. The structure was there, but then you have to embody it. We saw loads of people, I remember. But when Claire came in, she just was brilliant and just nailed it. Claire had the most difficult job of everybody because she had to start it. And the portrayal of the queen in this series is a woman who doesn’t really want any great fuss, wants to live at home with the horses and the dogs, and actually just wants to do the right thing. [She’s] an ordinary woman who’s put in extraordinary circumstances. You just had access to that woman. And the way Claire did that made everybody watch it, and really want to really engage with her. She set the bar. For all of these characters, you have to bear in mind not only who they are in the next chunk of their lives (in terms of the real-life characters), but who played them before, and how they played them.”

What was Claire Foy’s audition like?

“I remember she came in, and she was expecting a baby. I think I had to read with her. There was a scene with Churchill, I think. We did a couple of scenes. I just remember how brilliant she was. We were just like, ‘We’ve got the girl. She’s it.’ ”

Olivia Colman as Queen Elizabeth in The Crown, Season 4. 

Liam Daniel/Netflix

Imelda Staunton as Queen Elizabeth in The Crown, Season 6. 

Keith Bernstein/Netflix

How far in advance did The Crown cast Olivia Colman and Imelda Staunton?

“Once we’d seen what Claire was doing, we had to sit down and think, ‘Well, who is going to be next?’ Claire didn’t play the grandeur or the haughtiness or the majesty of the monarch. She played an accessibility, [so] you feel that you completely understand [her as a] woman. And there’s something [similar] about Olivia, there’s an accessibility to her, the idea of an ordinary woman in extraordinary circumstances. You feel you’ve got instant access to her. And that’s what she brought, which is taking over from what Claire brought to that part.

“And then you go on to Imelda [Staunton], who’s one of the finest that we’ve got in the UK, but also has an accessibility to her. She lets you in, and she was just the perfect next person. And when she said yes, we had a party.”

Viola Prettejohn as young Princess Elizabeth in The Crown, Season 6.

Who plays young Princess Elizabeth in Season 6?

“Viola Prettejohn. I knew that she looked like Claire Foy, so she came to mind. There were a couple of people who I thought of, but when we started putting the Elizabeths and Margarets together, it was clear. She had all the qualities of Claire Foy. She looked like her, but she had a kind of openness and a seriousness. There’s a bit of her that wants to break out of herself, but she’s holding herself back — all of those things that you associate with the way Claire played Elizabeth. [Viola] was like a mini version.”

Did any of the actors do chemistry reads?

“We’ve done quite a lot of chemistry reading over the years. We did chemistry reads with Meg and Ed [who play Prince William and Kate in Season 6], with Ed and Luther [who plays Prince Harry in Season 6]. I loved the chemistry read with Josh and Emma [Prince Charles and Diana in Season 4].

“Josh was in the middle of shooting, so we didn’t do it in a casting space. We went to one of the sets, some stately home somewhere, [after] they’d finished shooting for the day. It would’ve been one of [Prince Charles’ and Diana’s] quite high-octane scenes about their marriage problems. We sat in a big dining room, and just set up two chairs. I put my little camera on a tripod, and we just did it in there. And it was great. They understood their characters, they were interacting generously and openly, and there was a sweetness. It’s difficult to describe, isn’t it? With chemistry, you can see it.”

Watch The Crown Season 6 now.