The Diplomat EP And Keri Russell Break Down Jodie Whittaker's Debut As The New British PM

Warning: This post contains spoilers for the first five episodes of Season 4 of "The Diplomat."

Kate Wyler has a new British prime minister to contend with this season on "The Diplomat" — and she might be wishing she had Nicol Trowbridge back.

In Season 4 of the Netflix political thriller, the British PM Trowbridge abruptly resigned (after Kate threatened to expose his physical assault of Margaret Roylin), and he was replaced by Bethan Vaughn, a smart and ambitious young politician played by "Doctor Who" alum Jodie Whittaker. At first, Kate was relieved that she didn't get stuck with an ultra-conservative PM... but soon enough, she realized that working with Vaughn wouldn't be as easy as she thought.

"Bethan Vaughn is exactly what Kate wanted," showrunner Debora Cahn tells TVLine. "She's so much like Kate. They get along like a house on fire. They kind of look alike, and they have the same kind of attitude and set of values, and it should be the marriage made in heaven... and isn't." 

That unexpected friction between them "was the right set of hurdles and challenges to give to [Kate] at this point in the evolution of the show," Cahn adds. "She's created a playbook for how to manage Nicol Trowbridge, and he may be crazy, but he's her crazy, and she knows what it takes to manage that."

But as Cahn notes, "diplomats go to a different country every three years. Like, you're not allowed to stay. The second you know what you're doing, you're onto something else." So "it felt like the only honest thing to do was to throw [Kate] off-center in the way that people are all the time in that job."

Keri Russell, who stars as Kate, remembers that when Deborah Cahn first told her about the Bethan Vaughn character, "I think she really wanted to find somebody who was more of a peer to Kate. Because we have Grace Penn, who is so much more powerful and dignified and experienced, and I think she was interested in someone who was able to be more polished and keep her mouth shut and say the appropriate things in a way to show that juxtaposition." Plus, "it is interesting to have someone that is of your generation that you're looking in the eye and going, 'Well, I disagree... please see it from my side.'"

But Kate and Vaughn face a cultural divide right away, she points out: "The Brits are so full of pleasantries and polite talk, and Americans sort of say the honest truth way too often, and I think [with] Prime Minister Vaughn, there's a lot of that at the beginning. 'Oh, it's so nice to meet you.' And Kate's like, 'Seriously, stop dodging it. Like, what do you think about this?' And I need to have an answer. Like, 'Stop saying please and thank you so much.' And I think there's a bit of that [between them], which is culturally true, I find."

How did you like the addition of Jodie Whittaker this season on "The Diplomat"? Hit the comments below to share your thoughts.