In one of the final scenes of the first season of Netflix's critically exalted The Crown, the now established Queen Elizabeth II (Claire Foy) must bow to the will of her parliament and deny her sister Princess Margaret (Vanessa Kirby) permission to marry the divorced Group Captain Peter Townsend.
The exchange - if you could call it that - is notable more for what is not said than what is said out loud, as the two sisters, in the Queen's audience chamber, sit in stony silence, Elizabeth's now-broken promise to their father to look after Margaret weighing heavily on both of their minds.
While the first season focused heavily on the early days of Elizabeth's reign, and her marriage to Prince Philip (Matt Smith), the second season steps into the turbulent relationship between palace and parliament, and the contrast between the proper Elizabeth and wilful Margaret.
Speaking to Fairfax Media in London ahead of the launch of the second season, actress Vanessa Kirby says that scene was one of the most challenged the role of Princess Margaret has presented to her.
"Peter Morgan's writing is so much about what you don't say, you're saying one thing but there's 10 other things going on, and those are the best writers like Chekhov ... they're masters at a sort of naturalism and yet there is all the subtext," she says.
"Because that's what happens, it's subconscious, it's all the years of resentment and history between the sisters, ending up in that one moment."
To play it, she adds, offers a less clear way forward. "I had no idea how that scene had gone, I left the day going like, did I just f--- that up or not? Because you can play it so many different ways, I could have played that screaming in her face, you know?
The key, she says, was "really sort of taking your time with it and not being afraid of the silences and trusting that the audience will imagine and get things from the silences that maybe we don't do because we don't have to work as hard, really. I can be thinking all these things, but you guys sort of have to imagine or try to get in my head when I'm doing it."
Just as the series itself has been transformative for Netflix in terms of handing the relatively young streaming platform a piece of world-stopping cultural history, the roles of Elizabeth, Philip and Margaret have been transformative for Foy, Smith and Kirby.
Kirby concedes prior to The Crown she had little real knowledge of the modern royal family.
"You know at school you learn about Henry VIII and then Elizabeth but these guys ... I felt more detached from them than even the historic figures because I didn't really know what the relevance was," she says. "But I am so honoured that I got the opportunity to learn about them ... it gave me loads of empathy for them, I lost my judgments of them.
"And for Margaret in particular, I knew nothing about her other than she was quite a tragic figure later in life and she was the Queen's sister and that was it," Kirby adds. "So to get to know her as a girl, to see her whole journey and actually see the trauma at the kind of centre of her life, to get to play her and for it to be in the public consciousness is such a privilege."
The second season of The Crown retains its focus on the marriage of Queen Elizabeth II and Prince Philip, but deftly uses the relationships of two other couples to provide a contrast: US presidential couple JFK and Jackie O, who we meet on tour in Europe, and Princess Margaret and Antony Armstrong-Jones, later Lord Snowdon.
"They're all sort of different and dynamic and they're all meant to be in complete contrast of each other," Kirby says.
"There's a great scene in which everyone is getting ready for bed and it cuts between Elizabeth and Philip in separate bedrooms, Elizabeth praying and the lights go off, whereas Margaret has just met Tony, he's dropped her off on the motorbike and she starts undressing in front of the mirror and dancing.
"It points out the difference between the sisters yet again," Kirby adds. "And then you have the Kennedys, who represent this new force of modernity and ultra cool chic and I think in comparison Elizabeth feels a bit of a wet plant."
When she played the Queen in Morgan's film The Queen, actress Helen Mirren spoke at length about finding the character in her stance; though that iteration of Elizabeth's life was much later than the time period of The Crown.
For Kirby, Margaret's stance was distinct and she also found an unexpected touchstone for the wilful princess: cigarettes.
"The clothes really helped, we always designed things that sort of expressed her internal life," Kirby said. "And also the cigarettes, she was a mad smoker, she was never without one apparently and so it became a real signature thing.
"I found it very hard not to smoke in scenes by this season, because it was so part of her posture," Kirby adds. "She always had them on her, she's lighting one or smoking one in the middle of [every scene] and it was kind of like punctuation for her."
Kirby also turned to some unexpected sources, such as an interview that Margaret granted to the BBC radio program Desert Island Discs in 1981. While not quite an informal chat, there were glimpses of the real woman in her conversation with host Roy Plomley???.
"I found it incredibly revealing, very, very revealing," Kirby says. "I listened to all the music that she quoted as well as music related to that, that I thought she might like. I just love that she likes Scotland the Brave on the bagpipes, which is hilarious. And I read tons of different books, from the really scholarly ones to the really raunchy ones."
As a public figure, Margaret's royal life and social life were up for public consumption. What was rarely touched on, however, was the tremendous loneliness at the core of Margaret, which stems from losing her father, then her sister as she becomes the Queen, and finally being denied the love of her life, Peter Townsend.
"As soon as her father died, her world completely changed," Kirby says.
"She would have had a very different life had he not. And her loneliness is one of the things that come up most because Elizabeth was busy, [and] couldn't really support her ... usually you go through things as a family and it seemed like they really didn't."
Elizabeth was "busy having to be a new Queen and [focused on] Phillip and her children and the Queen Mother was very sort of trapped within her own grief and Margaret was isolated," adds Kirby.
"She really had to deal with her grief without anybody. She isn't allowed to marry Peter so who does she turn to? Who does she have?"
WHAT The Crown (season 2)
WHEN Netflix, from Friday, December 8