For viewers, The Crown offers a peek into a modern royal family's life and times, or at least an engaging dramatisation. For the cast, it's meant the lofty equivalent of gig work as the Netflix series ticks through the decades.
Claire Foy played Britain's young Queen Elizabeth II for the first two seasons, with Olivia Colman stepping in to chart her middle years last season and in the 10 new episodes out Sunday (Nov 15). Imelda Staunton ascends to the throne for the final two chapters.
When Diana Spencer makes her pivotal entrance this season, largely set in the 1980s, it's Emma Corrin in the part opposite Josh O'Connor's Prince Charles. Corrin's job is one and done: Elizabeth Debicki takes over in seasons five and six as the bound-for-tragedy Princess Diana, opposite a new, yet-to-be announced Charles.
A role in The Crown is akin to a relay-race baton destined to be handed off, said Helena Bonham Carter, back for her second whirl as tempestuous Princess Margaret. The actor is sandwiched between Vanessa Kirby (seasons one and two) and Lesley Manville, who will take Margaret across the finish line.
"I'm very sad that it's over, but it's time that she was played by somebody else at some point.... She's just a great gift of a part," Bonham Carter said during a joint interview with Colman and Tobias Menzies, returning as Prince Philip.
Colman called Staunton's casting "amazing", then suggested the newcomer could overshadow her. "It's almost, 'wish she wasn't quite good,'" she said, smiling. That prompted Bonham Carter to predict a battle of the stars after the series ends.
"Rate your Margarets, rate your queens, rate your Philips," she said, comparing it to "who wore it best" celebrity fashion critiques.
Colman was asked if she had any advice for her successor. Her terse reply: "Good luck. The wig's itchy."
The Crown casting director Robert Sterne said swapping out actors wasn't preordained when he began working with series creator and writer Peter Morgan.
It was an open question "whether we aged-up actors across their life span or were bold and we cast each time," Sterne said in an interview. Choosing the latter option meant a series of challenges and opportunities, for the show and its parade of actors.
"You spend a lot of time looking at the pictures and images of people at particular stages of their life" to find the right actor to portray them at a particular stage of their lives, he said. Then he invoked the relay-race analogy in citing another key stop.
"You also have to take into account the way that that previous actor portrayed it. Who do you think can take that baton and run with it?" he said, which he described as reinventing the role "but hopefully not in a jarring way".
Every move, especially a major cast change, is a critical one for the popular series that reportedly cost more than US$100 million for its first two seasons alone.
Actors, including illustrious ones, have been happy to accept hand-me-downs. Colman came to The Crown after winning an Academy Award and other honours for 2018's The Favourite, in which she played a far earlier British monarch, Queen Anne.
Staunton was an Oscar nominee for Vera Drake; Manville for Phantom Thread; Bonham Carter for The King's Speech and The Wings Of The Dove, and Jonathan Pryce, the future Prince Philip, for The Two Popes.
John Lithgow, another Oscar nominee and a rare American in the primarily British cast, had the part of political leader Winston Churchill to himself and snared an Emmy Award for it.
All those playing the pivotal role of Elizabeth are able to to convey "an ordinary woman put in extraordinary circumstances," Sterne said of the queen as portrayed in The Crown.
It requires an actor "who can carry you along with that, and make you feel for them and believe in the reality of it. They're all really extraordinary at that," he said. Foy won a 2018 Emmy for her performance.
There's also room on the royal family tree for younger, less familiar talent, including Corrin and Erin Doherty, who plays the queen's feisty daughter, Princess Anne, and proved a revelation.
"Actors will have this incredible connection with this character that you don't see coming," Sterne said. When Doherty auditioned, "she just had such a connection with that character. She'd watched a lot of YouTube videos (of Anne) and said, 'I just love this woman, I just know her, I think she's great'".
Doherty delivered in the tryout and in the series with a "really excellent" performance, Sterne said.
The casting veteran, who won three Emmys for his work on HBO's Game Of Thrones and a 2018 trophy for The Crown, found himself jumping into Corrin's audition. She was put on the spot by acclaimed writer Morgan (The Queen, Frost/Nixon) to sing Andrew Lloyd Webber's All I Ask Of You.
Sterne called up a karaoke version on a computer and offered to sing along.
"She was blushing as she was doing it, and sang it completely beautifully," Sterne recounted. "It was incredibly sweet and kind of encapsulated the spirit of Diana that we were looking for.... I thought, 'Well, this part isn't going to go anywhere else now'".
O'Connor said he relished his time on the series, including saying goodbye to a role he knew wasn't for keeps – just as with Shakespeare's works.
"If you play Hamlet, you know that there's 100 people who've played Hamlet before you, there's going to be 100 people after you," O'Connor said. "And they'll all do it differently, and that's the joy."