With how quickly Slow Horses is scoring renewed, it feels like the Apple TV+ drama can just keep going.

“I know that Gary [Oldman] has expressed a desire to play Lamb forever and that Mick [Herron] is still writing the books, so I hope it will go for as long as people want it,” Slow Horses executive producer Will Smith shared with TV Insider in October 2024.

Slow Horses follows Jackson Lamb and a team of British intelligence agents who serve in the dumping ground department of MI5 — Slough House — due to their career-ending mistakes.

The fifth season will premiere in September 2025, but already, the show has been renewed for its sixth and seventh. But what about beyond that? Read on for everything we know about a Slow Horses Season 8, from the cast to the Mick Herron book on which it could be based.

Has Slow Horses been renewed for Season 8?

No — at least not yet. But it’s still very early, and even if it is renewed, we wouldn’t expect an announcement until before the sixth season is released.

On which Mick Herron book would Slow Horses Season 8 be based?

The first five seasons of Slow Horses each cover one book of Herron’s series: Slow Horses, Dead Lions, Real Tigers, Spook Street, and London Rules. Season 6 is based on the sixth and seventh books, Joe Country and Slough House. Bad Actors, the last novel published, will be adapted for Season 7.

Should the series continue beyond Season 7, there are also novellas and a full-length novel titled Clown Town, which is set to be published on September 9, 2025, that could be adapted. The synopsis of Clown Town reads:

“‘Old spies grow ridiculous, River. Old spies aren’t much better than clowns.’ Or so David Cartwright, the late retired head of MI5, used to tell his grandson. He forgot to add that old spies can be dangerous, too, especially if they’ve fallen on hard times — as River Cartwright is about to learn the hard way.

David Cartwright, long buried, has left his library to the Spooks’ College in Oxford, and now one of the books is missing. Or perhaps it never existed. River, once a “slow horse” of Slough House, MI5’s outpost for demoted and disgraced spies, has some time to kill while awaiting medical clearance to return to work, and starts investigating the secrets of his grandfather’s library.

Over at the Park, MI5 First Desk Diana Taverner is in a pickle. An operation carried out during the height of the Troubles laid bare the ugly side of state security, and those involved are threatening to expose details. But every threat hides an opportunity, and Taverner has come up with a scheme. All she needs is the right dupe to get caught holding the bag.

Jackson Lamb, the enigmatic and odiferous head of Slough House, has no plans to send in the clowns. On the other hand, if the clowns ignore his instructions, any harm that befalls them is hardly his fault. But they’re his clowns. And if they don’t all make it home, there’ll be a reckoning.”

Smith had also revealed to TV Insider in October 2024, “Mick has talked about doing a standalone, not from a book, so I’m sure that’s possible” and that there’s quite a bit of “material in the Slough House world to be mined,” including “a couple of novels that Mick’s done that introduced characters that then come into Slough House that flesh out the backstories.”

Who could be in the Slow Horses Season 8 cast?

Season 5 stars Gary Oldman (Jackson Lamb), Kristin Scott Thomas (Diana Taverner), Jack Lowden (River Cartwright), Saskia Reeves (Catherine Standish), Rosalind Eleazar (Louisa Guy), Christopher Chung as (Roddy Ho), Aimee-Ffion Edwards (Shirley Dander), Ruth Bradley (Emma Flyte), James Callis (Claude Whelan), Tom Brooke (J.K. Coe), and Jonathan Pryce (David Cartwright).

We’ll have to wait to see the events of Seasons 5, 6, and 7 to begin speculating about who would be back.

When would Slow Horses Season 8 premiere?

Should the series be renewed, it does seem likely that an eighth season wouldn’t be released until 2027 or even 2028.

Season 1 was released in April 2022, Season 2 in December 2022, Season 3 in November and December 2023, and Season 4 in September and October 2024. Season 5’s release will be in September and October 2025. Season 6, which has already been filmed, will likely be in 2026. Season 7 could be in late 2026 or 2027, so Season 8 would be after that.

Slow Horses, Season 5 premiere on Sept. 24, Apple TV+