Why Slow Horses Showrunner Is Leaving After Season 5, Explained By The Man Himself [Exclusive]

"Slow Horses" season 5 has proved the series is still one of the best on Apple TV+, with Gary Oldman's Jackson Lamb and his band of outcasts returning for yet another solid season of dodgy spycraft. Since season 1, the show has been overseen by Will Smith, who was charged with bringing Mick Herron's "Slough House" novel series to TV. Smith previously wrote for political satires on both sides of the pond, contributing to "The Thick of It" in the United Kingdom and "Veep" stateside. Both shows were overseen by Scottish satirist Armando Iannucci, and prepared Smith to bring an unmistakably irreverent tone to "Slow Horses." Of course, that tone was already there in Herron's novels, but you couldn't imagine a better showrunner to adapt those books for the small screen. Which is why it's a real shame, and sort of surprising, that Smith is departing the show following season 5.

/Film's Ben Pearson spoke with the "Slow Horses" showrunner and asked about his departure from the series. It seems Smith wasn't exactly enthused about leaving, with the writer revealing that it was "a practical decision" more than anything else, mostly "based on the looming need for scripts for series 6." As Smith explained, "I was doing so much work on series 5 that there was no way I was going to be able to do that. I don't want to leave, but it was also like, I couldn't get the scripts ready, they couldn't meet the schedule, so it was with great sadness on both sides."

Bidding farewell to Smith seems like one of the most fatal mistakes Apple could make considering how well he's shepherded the show thus far and how well-suited to the material he's proved to be. All of which only adds to the confusion surrounding his leaving — though the show's intense production schedule clearly has a lot to do with it.

Though it still hasn't received the widespread recognition it deserves, "Slow Horses" has been the best spy show on TV ever since its 2022 debut. A big part of that is down to Smith, whose departure from the series leaves a lot up in the air. While the show is driven by some of the best performances on the small screen, most notably Gary Oldman's portrayal of the jaded slob of a sleuth that is Jackson Lamb, there's no doubt that Smith's sensibility is partly why "Slow Horses" works so well and is slowly but surely managing to build momentum among audiences. (It doesn't help the show is on Apple TV+, which is not only losing a ridiculous amount of money, but also has several standout shows that nobody is watching.)

According to Smith, however, he feels as if he's leaving at an ideal time in terms of the show's progression. "In terms of my contribution, I feel it does conclude certain arcs that were started in series one," he told /Film. "I don't want to give any spoilers, but it feels like a nice place to exit. The show is in a good position, I hope, creatively." The finale of season 5 certainly sounds like a turning point for the show, but just where it will turn sans Smith remains to be seen. But it's not as if there's a lack of source material. As the now-former showrunner said during his interview, "The show is going to go on to even bigger and better things and Mick [Herron] has just released the ninth book, and I'm sure there'll be a 10th, 11th, 12th. So it's going to go on and on." Let's hope whoever takes over from Smith manages to maintain the quality throughout that process, especially since the showrunner wasn't entirely happy about leaving.

Will Smith's departure from "Slow Horses" isn't the best news for the show. But considering how quickly Apple is churning out these seasons, it's understandable that Smith might want a break. "Slow Horses" has an unorthodox shooting schedule, whereby Apple shoots two seasons back to back so it can release one season per year.  Deadline confirmed that season 6 is already filmed and that season 7 was set to start shooting in September 2025, and Smith has spoken previously about writing one season while shooting another and editing yet another. That's a heck of a workload that any showrunner would struggle to keep up with. 

Still, you'd have thought Apple would have done all it could to keep Smith onboard, even if he juggled showrunning with someone else and they took turns producing each season. For now, it seems Gaby Chiappe ("The Level") is handling season 6 while "All Creatures Great and Small" creator Ben Vanstone oversees season 7. Thankfully, with a cast as good as the "Slow Horses" ensemble and Herron's books to fall back on, there's every chance the new seasons will be as good as the previous ones.

"Slow Horses" season 5, episode 1 is streaming on Apple TV+ now.