You remember that feeling when a character walks onto the screen and just… fits? That was Sonya Cassidy in The Last Kingdom. She showed up in Season 5 as Eadgifu, and honestly, she felt like she’d been there since the pilot. It’s a rare thing in a show that’s already four seasons deep and packed with heavy hitters like Alexander Dreymon.
But then, the movie Seven Kings Must Die dropped. And people were confused. Like, really confused.
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Why did the face change? Where did Sonya go? There’s a lot of noise online about why she left, but the truth is actually pretty boring—yet it tells you everything about how the TV industry works in 2026.
The Eadgifu Switch: Why Sonya Cassidy Left The Last Kingdom
Let's clear the air. There wasn't some massive behind-the-scenes drama. No one got fired. Nobody stormed off set in a huff.
Basically, it was just the "scheduling gods" being cruel. When Netflix greenlit the follow-up movie, Seven Kings Must Die, the production window slammed right into Sonya Cassidy’s other commitments. At the time, she was moving on to projects like The Man Who Fell to Earth.
In an interview with The Digital Fix, Sonya admitted she had a "heavy heart" about not returning. She loved the role. She loved the Budapest set. But you can't be in two places at once, even if you’re playing the future Queen of England.
Who took over the role?
Because the character of Eadgifu was historically essential to the story of King Aethelstan and the unification of England, the producers couldn't just write her out. They brought in Elaine Cassidy.
Yeah. Another Cassidy. No relation.
It was a bit of a trip for fans. Elaine is a fantastic actress—you might know her from A Discovery of Witches—but she brought a totally different energy. While Sonya’s Eadgifu felt like a breath of fresh air and a burgeoning romance for King Edward, Elaine’s version was hardened, older, and deeply protective of her son, Edmund.
What Sonya Cassidy Brought to Season 5
Before the recast, Sonya Cassidy’s Eadgifu was a pivotal turning point for the show. Up until then, King Edward’s love life was... well, a mess. He was surrounded by schemers, particularly the Aethelhelm family.
Then comes Eadgifu of Kent.
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She wasn't just another lady-in-waiting. Sonya played her with this incredible blend of Kentish grit and courtly grace. She was the one who finally saw through the fog of Edward's indecision.
- The Chemistry: Her scenes with Timothy Innes (King Edward) were some of the most natural in the later seasons.
- The Political Power: She wasn't just a love interest; she was a strategist.
- The Grounding Force: In a season filled with prophecy and blood, she represented the "civilized" future of England.
The Real History vs. The Show
Fans of The Last Kingdom often forget that Eadgifu wasn't just a character created for the Uhtred saga. She was a massive deal in real Anglo-Saxon history.
The real Eadgifu of Kent was the third wife of Edward the Elder. Sonya’s portrayal captured that "outsider" status perfectly. In reality, she survived Edward and became a powerful "Queen Mother" figure, influencing the reigns of her sons, Edmund and Eadred.
Honestly, that’s why the recast felt so jarring for many. Sonya had built the foundation of a woman who was supposed to rule for decades. Seeing that mantle pass to someone else mid-stream felt like a glitch in the Matrix.
Breaking down the performance
What made Sonya’s take work so well? It was the eyes. She has this way of looking at a scene where you can see the gears turning. In The Last Kingdom Season 5, Eadgifu has to navigate a court that literally wants her dead or exiled. Cassidy played that fear with a layer of "don't mess with me" underneath it.
Where is Sonya Cassidy Now?
If you're missing her on your screen, don't worry. She hasn't slowed down.
While she missed the finale of the TLK universe, she’s been busy making a name for herself in even bigger franchises. Most recently, she’s been making waves in Season 3 of Reacher. Playing Susan Duffy, she’s trading in the Saxon linens for modern-day grit, and the reviews have been stellar.
She’s also known for:
- Lodge 49 (The cult favorite where she played Liz Dudley)
- Humans (As the synth Hester)
- The Man Who Fell to Earth (Edie Flood)
It’s a bit of a bummer we didn't get to see her stand alongside Uhtred at the gates of Bebbanburg in the final movie. But that's the trade-off. To get a Sonya Cassidy in your show, you have to accept that she’s in high demand.
Making Sense of the Legacy
So, what’s the actionable takeaway for a fan?
First, don't skip Season 5 just because the movie changes things up. Sonya Cassidy’s performance is the reason you care about Eadgifu in the first place. She took a character that could have been a footnote and turned her into the heart of the Winchester court.
Second, if you're a "completionist," watch Season 5 and then immediately watch Seven Kings Must Die. It’s easier to handle the recast if you view them as two different chapters of a woman’s life: Sonya represents the rise to power, and Elaine represents the struggle to keep it.
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If you want to dive deeper into her work, check out Lodge 49. It’s a completely different vibe, but it shows the range that made her so perfect for The Last Kingdom in the first place.
Go back and re-watch the scene where Eadgifu first meets Edward. Notice the lack of hesitation in her voice. That wasn't just good writing; that was Sonya Cassidy owning the room.
Next Steps for Fans:
- Watch Season 5, Episodes 1-10: Pay attention to how Eadgifu transitions from a petitioner to the King's closest advisor.
- Compare the Portrayals: Watch the first 20 minutes of Seven Kings Must Die to see how the tone shifts with the recast.
- Track her Career: Follow her transition into the Reacher universe, which offers a modern look at her action-oriented acting style.