Complete cast breakdown of Slow Horses Season 5: Who plays who & where you’ve seen them before

Slow Horses is Apple TV+'s acclaimed spy thriller series based on Mick Herron's Slough House novels. It follows the rejects of MI5's Slough House, a dingy department for failed agents. Led by the slovenly genius Jackson Lamb, they stumble into national threats through sheer incompetence and grit.

The books mix sharp satire with high-stakes espionage, poking at bureaucracy and British intelligence. Screenwriter Will Smith adapted the first season in 2022. It premiered on April 1 that year.  Season 5 adapts London Rules, Herron's fifth book. It centers on a terrorist attack on a shopping center blamed on a far-right group. 

The plot is tied to London Mayor Zafar Jaffrey's reelection and MI5's internal power struggles. The series has earned three BAFTA nominations and a 98% Rotten Tomatoes average. Season 5 premiered on September 24, 2025 on AppleTV+.

Slow Horses season 5: Complete cast breakdown

• Gary Oldman plays Jackson Lamb, the brilliant leader of Slough House. Seen as Winston Churchill in Darkest Hour, Sirius Black in Harry Potter and George Smiley in Tinker Tailor Soldier Spy.

• Jack Lowden plays River Cartwright- the disgraced MI5 heir chasing redemption seen as a young pilot in Dunkirk, Lord Loxley in Mary Queen of Scots and in War & Peace.

• Kristin Scott Thomas plays Diana Taverner- the icy, power-hungry MI5 Second Desk seen in The English Patient, Four Weddings and a Funeral and Fleabag Season 2.

• Saskia Reeves plays Catherine Standish- the loyal office anchor. Seen in Luther, Close My Eyes with Clive Owen and Salting the Battlefield.

• Rosalind Eleazar plays Louisa Guy, the sharp field agent who exits tragically. Seen in The Capture, Deep State and Harlots.

• Christopher Chung plays Roddy Ho, the arrogant hacker with a deadly new girlfriend; seen in Waterloo Road, Into the Badlands and Doctor Who (2025).

• Aimee-Ffion Edwards plays Shirley Dander, the coke-fueled loose cannon; seen as Esme Shelby in Peaky Blinders, Sketch in Skins and Detectorists.

• Kadiff Kirwan plays Marcus Longridge, the gambling-addicted sharpshooter, seen in This Way Up, The Stranger and Chewing Gum.

• Tom Brooke plays J.K. Coe, the traumatized, silent ex-Psych Eval agent; seen in Preacher as Fiore, Sherlock (“The Lying Detective”) and Bodyguard.

• James Callis plays Claude Whelan, the overwhelmed MI5 First Desk; seen as Gaius Baltar in Battlestar Galactica, Bridget Jones’s Diary and Castlevania (voice).

• Ruth Bradley plays Emma Flyte, the ruthless Head of the Dogs; seen in Humans, Love/Hate and The Fall.

• Jonathan Pryce plays David Cartwright, River’s legendary, fading spy grandfather; seen as the High Sparrow in Game of Thrones, the Pope in The Two Popes.

• Samuel West plays Peter Judd MP, the pompous, far-right Home Secretary; seen as Siegfried in All Creatures Great and Small, Anthony Blunt in The Crown, and Mr Selfridge.

• Hugo Weaving plays Frank Harkness, the shadowy ex-agent with old debts; seen as Agent Smith in The Matrix, Elrond in The Lord of the Rings and V in V for Vendetta.

• Nick Mohammed plays Zafar Jaffrey, the slick, embattled London Mayor; seen as Nathan Shelley in Ted Lasso, Piglet in Winnie-the-Pooh and Intelligence.

• Victoria Hamilton plays Dodie Gimbal- Dennis’s fiery columnist wife; seen as Queen Mother in The Crown, Mansfield Park and Scoop.

• Hiba Bennani plays Tara, Roddy’s glamorous, suspicious girlfriend.

Stream all episodes of Slow Horses Season 5 on Apple TV+.

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