Slow Horses novels writer reveals there are "a lot of departures from the book" in season 5
Mick Herron said he enjoyed the changes from the novel and in fact instigated some of them himself.
The fifth season of Apple TV+ hit Slow Horses, which will start airing next week, is based on the fifth novel in Mick Herron's Slough House book series, London Rules - but readers may find the season quite different than the story they remember.
Speaking exclusively with RadioTimes.com at a special An Evening with Radio Times screening for Slow Horses season 5 at the BFI, Herron said he thought that the new instalment was "fantastic".
When asked whether he was surprised by anything in the adaptation, he said: “Not a surprise because I’ve been involved in the adaptation and as such I discussed any changes they were making.
"But there are a lot of interesting departures from the book which I enjoyed. Some of which I instigated..."
Earlier this year, when speaking with Radio Times, Herron praised the show's faithful depiction of his characters, and revealed he was always happy for adjustments to be made to the plots as long as that was in place.
He said of the show as a whole: "It's done with such enormous fidelity to the characters – not to the plots, which is not important to me, but to the characters, which is important to me – that the difference is purely one of transmission. [Showrunner Will Smith] totally, as do the other writers, gets the mood and tone of the books."
The synopsis for season 5 reads: "Everyone is suspicious when resident tech nerd Roddy Ho has a glamorous new girlfriend, but when a series of increasingly bizarre events occur across the city, it falls to the Slow Horses to work out how everything is connected.
"After all, Lamb knows that in the world of espionage, the London Rules – cover your back – always apply."
The season sees the return of stars including Gary Oldman, Jack Lowden and Kristin Scott Thomas, while Nick Mohammed joins the cast as Zahar Jaffrey, the London Mayor.
Mohammed has said that comparisons between his character and the real-life Mayor of London Sadiq Khan are inevitable – but that the character is based on "lots of different politicians".
Slow Horses season 5 releases on 24th September 2025 on Apple TV+ – sign up to Apple TV+ now.
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Authors
James Hibbs is a Drama Writer for Radio Times, covering programmes across both streaming platforms and linear channels. He previously worked in PR, first for a B2B agency and subsequently for international TV production company Fremantle. He possesses a BA in English and Theatre Studies and an NCTJ Level 5 Diploma in Journalism.
