One of the most exciting additions to The Crown Season 4 is Gillian Anderson, who plays former Prime Minister Margaret Thatcher. Thatcher looms large in the annals of history, bearing the distinction of being the first woman to hold the position of Prime Minister and proceeding to become an extremely polarizing figure over the course of her 11 years in office. Thatcher's working relationship with Queen Elizabeth II (played by Olivia Colman for a second and final season) will be one of the key focal points of Season 4, with their politely adversarial feelings seemingly coloring every encounter they have. With two powerhouse actors — Colman and Anderson — coming together to play two figures who are also powerhouses in their own right, one has to wonder what it was like bringing this unique relationship to the screen.

Luckily for Collider, we didn't have to wonder too long. Earlier this year, we participated in a panel discussion for The Crown Season 4 that featured Colman, Tobias Menzies (Prince Philip), and Helena Bonham Carter (Princess Margaret). During the panel's chat about the new season, the subject of Elizabeth and Thatcher's relationship was addressed. Things kicked into high gear when Colman was asked about her approach to developing Elizabeth's relationship with Thatcher and the preparation that went into those scenes opposite Anderson. Now, it's been a while since Colman was on set filming The Crown Season 4, so the Oscar winner's memory was slightly fuzzy on specific scenes and prep work.

However, the conversation was guided toward the ways in which Thatcher's private audiences with Elizabeth (which, as with past seasons, becomes a regular occurrence in Season 4) exposed both Thatcher's vulnerability which laid underneath her stern exterior, and how those audiences offered a chance to show how very different two women who were the same age in similar positions of power interacted with each other. Colman touched on this, recalling, "[Season 3 Prime Minister] Wilson (Jason Watkins) was so awkward and they [Wilson and Elizabeth] ended up having a really lovely friendship. I mean, it's daunting and terrifying. You spend your whole life with sort of this political drive and then suddenly, 'Oh I forgot that was going to happen. I've got to go and see the Queen every week! Grr, I'd forgotten that bit.' And so yes, Thatcher — yes, I really wish I could remember [that scene] — there were lots of funny moments between Thatcher and the Queen in our version."

Colman went on to remark that Elizabeth and Thatcher's relationship is "sparky": "The queen, sort of, for what we've done, was excited about having a woman around — and it didn't last."

And when it came to acting opposite Anderson, Colman readily shared just how daunting a task it was. The first images from the new season teased a thoroughly transformed, nearly unrecognizable Anderson in her Thatcher costume and make-up. Colman commented on how Anderson's transformation was so uncanny that it made filming scenes a real thrill.

"So much of our job is done for us by incredible hair and make-up teams and wardrobe. You know, if we turned up like this [refers to modern clothes] it wouldn't be as good and, you know, thank God for them. With Margaret [Thatcher], they really outdid themselves because it was sitting opposite her, especially when the light was behind her a bit, that [makes unnerved sound]...and Gillian's voice [...] and her walk."

It was at this point that Bonham Carter offered her two cents on Anderson's uncanny transformation, eliciting chuckles amongst the group. The actor remarked that "it was very funny. It just, unfortunately, was very difficult to keep a straight face because it was uncanny. It was like having a ghost around."

The Crown Season 4 launches on Netflix on Sunday, November 15. For more, check out Collider's own Matt Goldberg reviewing the new season.

Allie Gemmill is the Weekend Contributing Editor for Collider. You can follow them on Twitter @_matineeidle.