Olivia Cooke Returns to ‘Slow Horses’ for Season 6

Slow Horses started as a slow-burn sleeper hit for Apple TV when it premiered in April 2022, and while Season 2 was already planned, some of the actors wound up taking other jobs in the meantime. One cast member, in particular, landed a role big enough to necessitate an exit, especially since it was part of a franchise famous for a filming schedule that blocked the actors in it from doing other shows; I am, of course, talking about Olivia Cooke, who played Sidonie “Sid” Baker in the first season, only to have her character exit when she landed the role of Alicent Hightower in House of the Dragon.

As a British-ish show, we don’t cover the Westerosi-set series in depth here, but it’s common knowledge the prequel hasn’t nearly had the same level of success as the original Game of Thrones. Moreover, with the latest series, A Knight of the Seven Kingdoms, succeeding where House of the Dragon failed with critics, and the showrunner promising the series will conclude with Season 4, there’s been more room for the cast to take other roles, allowing Cooke to return to Slough House.

While Cooke’s return in Season 6 is technically billed as a guest star turn, bringing back Baker to the team has been something book fans have been hoping for. Here’s to Sid’s return to the series, and here’s to hoping Cooke sticks around for Season 7.

Here’s the Slow Horses synopsis for Season 6:

Slow Horses is a darkly humorous espionage drama that follows a dysfunctional team of British intelligence agents who serve in a dumping ground department of MI5 known un-affectionately as Slough House, run by Jackson Lamb, the brilliant but cantankerous leader of the spies who end up in Slough House due to their career-ending mistakes and who frequently find themselves blundering around the smoke and mirrors of the espionage world. Season 6 sees the Slow Horses on the run as Diana Taverner embroils them all in a fatally high-stakes game of retaliation and revenge.

Along with Season 1 cast member Cooke (The Girlfriend) returning as Sid Baker, Gary Oldman (Oppenheimer) returns for Season 6 as Jackson Lamb, with co-leads Jack Lowden (The Gold) as River Cartwright, and Kristin Scott Thomas (Rebecca) as Diana Taverner. They’ll be joined by longtime series regulars Saskia Reeves (Roadkill) as Catherine Standish, Rosalind Eleazar (The Personal History of David Copperfield) as Louisa Guy, Christopher Chung (Blitz) as Roddy Ho, Aimee-Ffion Edwards (Wolf Hall) as Shirley Dander, and Jonathan Pryce (The Crown) as David Cartwright.

The newer ensemble members who came aboard in Season 4, including Hugo Weaving (Patrick Melrose) as Frank Harkness, Joanna Scanlan (The Larkins) as Moira Tregorian, Ruth Bradley (Guilt) as Emma Flyte, and Tom Brooke (Bodyguard) as J.K. Coe, all return as well. Samuel West (All Creatures Great & Small) returns as Home Secretary Peter Judd after sitting out Seasons 4 and 5. Season 6 also adds Lenny Rush (Doctor Who) to the roster in an as-yet-undisclosed role.

Gaby Chiappe, who takes over from Slow Horses’ longtime lead writer, Will Smith, adapted Season 6, with Season 4 director Adam Randall returning to helm all episodes. Chiappe, Randall, and Oldman are listed as executive producers, alongside Jamie Laurenson, Hakan Kousetta, Julian Stevens, Iain Canning, Emile Sherman, Gail Mutrux, and Douglas Urbanski.

Slow Horses Season 6 is set to debut on Wednesday, September 16, 2025, followed by one episode per week through October. Season 7 is expected to follow in 2027. Seasons 1 through 5 are streaming on Apple TV.