The Crown stars Elizabeth Debicki and Dominic West break down climactic face-off between Charles and Diana

Warning: This post contains spoilers from episode 9 of The Crown.

Season 5 of The Crown depicts the separation of Prince Charles and Princess Diana and the ensuing, and often acrimonious, fall-out. Charles attempted to push his side of the story by agreeing to participate in a 1994 documentary Charles: The Private Man, the Public Role, which was partly overshadowed by the so-called "Revenge Dress" worn by Diana on the night the doc screened. The Princess agreed to be interviewed by Martin Bashir on a 1995 episode of the current affairs show Panorama during which she famously referred to Charles' affair with Camilla Parker Bowles saying, "There were three of us in this marriage, so it was a bit crowded." Given the hostile nature of the pair's relationship during the '90s, the actors playing the couple on season 5, Dominic West and Elizabeth Debicki, share little-to-no screen time for the bulk of the season. Then, in episode 9, their characters meet for a 12 minute-plus sequence at Diana's Kensington Palace residence, set after the details of their divorce have been settled, during which Charles and Diana discuss their marriage and its collapse.

"That's an incredible scene," says Debicki. "Dom and I started calling it our 'one-act play' when we read the script, and we would rehearse it, because it's quite a long scene. Yeah, it was an amazing scene to play, a real joy as an actor to have that kind of material. It's really rare to have material that is that well-written really."

Netflix Dominic West and Elizabeth Debicki on 'The Crown'

Charles' visit to Kensington Palace is prompted by a comment from his mother, Imelda Staunton's Queen Elizabeth, that the couple's divorce "cannot have been easy for Diana either."

"Honestly I'm not quite sure why I'm here," Charles tells Diana, after arriving unexpectedly at her apartment. "All I know is, I got in the car this morning and it just sort of drove itself here."

"If I'd known I would have put on a revenge dress," jokes Debicki's Diana.

"Haven't you been wearing one of those every day since our separation?" Charles responds with a smile.

Eventually, the Prince suggests "a review of marriage...no judgments, no arguments, just lay it out on the table."

What ensues does indeed resemble a self-contained mini-play as they discuss their marriage, the divorce, their friends, the pressure of their situation as a couple, Charles' relationship with Camilla, Diana's interview with Bashir, and Prince William who, Diana tells Charles, "everyone would prefer to see as King, not you."

Starting off with lightness and humor, plus a spot of egg-cooking on the part of Debicki's Diana, the tone becomes increasingly dark and acrimonious.

"You know, I came here today racked by guilt and uncertainty, and sad for what the country had lost, and sorry for my part in it," Charles announces to Diana at the conclusion of this "no judgments" marriage review. "But I leave here liberated, and more certain than ever that only with you out of my life and out of this family, can anyone find the happiness and the stability that's eluded us for 16 years years." The future King then leaves, with Diana's determined smile turning to tears after his departure.

"It was wonderful to have an imagined scene where there is a rapprochement between these two, who had been through so much, so publicly," says West of the sequence. "It felt right and interesting for them to reflect a bit about that, about being these rock stars really, bigger than rock stars, and also to reflect on the appalling pressures that had been upon them, and in some ways reflect on what had gone right and what was good about the marriage."

Netflix Dominic West and Elizabeth Debicki on 'The Crown'

Episode 9, titled "Couple 31," was directed by Christian Schwochow and written by The Crown creator Peter Morgan who, West reveals, visited the set as he and Debicki started fliming the sequence.

"We got to shoot it in plenty of time, I think we had four days," says the actor. "I remember Peter turned up to watch it on the first day. Whenever the writer's in the room behind the camera, you get slightly on edge, and so we spent the first few hours of Peter being there, making an omelette in silence. [Laughs] And we kept going, 'Is this going to make it to the final cut?' And of course it didn't. But it was a way of Christian, I think, protecting us from having the writer in the room, and Peter eventually went, 'Oh god, I'm off then, I'll let you get on with it.' And he did."

Debicki explains that some lines read differently to the actress on the day than they had when she first read them.

"The writing on this show is so excellent, and there are scenes that are so excellent, and you sit there as an actor, sort of what happens with theater texts, you sit there as an actor and you just gently look through each line and the pennies drop," she says. "I look at that scene and then four months later I'm looking at that scene and different pennies are dropping: oh, that's what that could mean, maybe this is what we should explore. You come to play it and it presents itself as a completely different question. It's just the best kind of joy you get as an actor to have that kind of material."

Debicki is proud of the result and believes that, while the sequence concerns two of the most famous people who ever lived, the scene will personally resonate with many viewers.

"It's Princess Diana and Prince Charles as characters but it's also the most human of questions in terms of love and relations and marriage," says the actress. "If you got to speak, if you really got to lay something out on the table, with a person who you loved so deeply, and therefore always will, what would you say? It poses this, I think, very provocative and moving kind of question. I know myself, personally, when I read it, of course, it brings those things up in my history, my personal history, and I think that it has the possibility to do that, which of course good drama does."

Season 5 of The Crown is now available to watch on Netflix.

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