Anna Madeley and Samuel West in All Creatures Great and Small Season 4 (Photo: Playground Entertainment and Masterpiece)

For years, the simmering romance between Siegfried Farnon (Samuel West) and Mrs. Hall (Anna Madeley) has been more of a "won't-they" than a "will-they," but that finally stands to change in the wake of the All Creatures Great and Small Season 4 finale, "The Home Front."

Though Siegfried and Mrs. Hall end the season in uncharted territory, their romantic prospects weren't looking good heading into the episode. All signs pointed to Mrs. Hall, now free to remarry after learning her divorce has been finalized, leaving the Yorkshire Dales with Gerald (Will Thorp), her kind, garden-loving boyfriend. They made plans to move to the Lake District, where Gerald's sister has been recovering from an illness, and even got engaged, with Mrs. Hall proclaiming that "this is [their] chance to be together," and if they don't take it, they "might always regret it."

[Spoilers for the All Creatures Great and Small Season 4 finale, "The Home Front."]

"The Home Front" picks up just a few weeks after their (ring-free, extremely chaste) engagement, and the confidence that motivated Mrs. Hall to say yes to Gerald's proposal has been replaced by a pervasive feeling of anxiety. She's already reluctant to tell Siegfried that she'll be quitting after 10 years as his housekeeper, but when crises begin to mount, she becomes even less sure of her decision.

The potential impact of her departure hits Mrs. Hall like a ton of bricks. How will Siegfried manage without his closest confidante, especially with his brother Tristan (Callum Woodhouse) and veterinary partner James (Nicholas Ralph) away serving in World War II? Who will guide Helen (Rachel Shenton) through the birth of her first child? And how will that bloody sink get fixed if Mrs. Hall's not around to ignore Siegfried's posturing and call a plumber?

These interconnected problems and the passionate response they elicit from the residents of Skeldale House emphasize just how needed Mrs. Hall is in Darrowby. That's nothing new; All Creatures has always posited that Mrs. Hall is the connective tissue holding this group together in ways both literal (she cooks, cleans, and tends to the veterinarians' material needs) and figurative (she's the only one able to navigate Siegfried's mercurial temperament and bring warring factions together, regardless of the issue). More than that, though, the events of the finale force Mrs. Hall to confront the unspoken truth about her position: Just as Siegfried, Helen, and new veterinary student Richard Carmody (James Anthony-Rose) rely on her to keep their lives afloat, she relies on them to give her a sense of purpose and a deep well of emotional support.

It's with this knowledge in mind that Mrs. Hall walks to Gerald's home and informs him that she can't move to the Lakes with him. She frames it as a temporary setback — "I don't think I'm ready to go, not just yet," she tells him — but they both know that's not the case. When Gerald gives her an out by breaking things off, he does so with a resigned sigh. "I've always known this would come," he says. "Perhaps it were never meant to be, you and me."

Gerald is inoffensive and easygoing, but he's not naive — even he can see that someone else would be a better fit for Mrs. Hall. His comment may be the show's most explicit acknowledgement yet of the slow-burn romance between Siegfried and Mrs. Hall. Fans have been clamoring for the two to get together since Season 1, but creator Ben Vanstone has resisted giving in to temptation, save for a few longing looks and some jealous behavior on Siegfried's end.

But while their physical connection remains unexplored, their emotional bond has flourished, particularly throughout Season 4, which saw them embrace their roles as the mother and father of Skeldale House more than ever before. By the finale, their relationship has become such an integral part of their lives that Siegfried can barely bring himself to read her resignation letter. When he finally does, they have a deeply vulnerable conversation about how they healed each other after their respective tragedies — for Siegfried, the death of his wife Evelyn, and for Mrs. Hall, her estrangement from her husband and son, Edward. That kind of introspection doesn't come easily to Siegfried, but Mrs. Hall has teased it out of him over the years, and both are better off for it.

With her ex-husband and Gerald out of the way, the door is at long last open for Siegfried and Mrs. Hall's intimate connection to transform from platonic to romantic. Acknowledging their mutual dependence on one another was the first step; now, someone must take the leap and bring a surge of passion to their stable, trusting relationship. The only question is, will Siegfried or Mrs. Hall make the first move?

The All Creatures Great and Small Season 4 Christmas special airs Sunday, February 18 at 9:00 PM ET on Masterpiece on PBS. Join the discussion about the show in our forums.

Claire Spellberg Lustig is the Senior Editor at Primetimer and a scholar of The View. Follow her on Twitter at @c_spellberg.