Lenny Rush is joining the cast of Slow Horses for the new series.

It has not been revealed what character the Bafta-winning Am I Being Unreasonable? star will play but an image of Rush in Slow Horses has been released as part of a first look at series six, starring Sir Gary Oldman. The six-episode sixth season will premiere globally on Wednesday, September 16, 2026 with the first episode, followed by one episode weekly until October 21, 2026.

“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. Oldman stars as 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 six sees the Slow Horses on the run as Diana Taverner embroils them all in a fatally high-stakes game of retaliation and revenge. The ensemble cast also includes Kristin Scott Thomas, Jack Lowden, Saskia Reeves, Christopher Chung, Aimee-Ffion Edwards, Rosalind Eleazar, Joanna Scanlan, Samuel West, Ruth Bradley, Tom Brooke, Jonathan Pryce and Hugo Weaving.

“Slow Horses” has been celebrated as “undoubtedly the best spy series on television,” a “truly epic espionage thriller” that is “utterly brilliant” and just “so damn good.” All five seasons of “Slow Horses” hold a Certified Fresh score, with two seasons receiving a rare, perfect 100% critics’ score on Rotten Tomatoes, and the series continues to receive global accolades from critics and fans alike.

Pictured - Lenny Rush and Christopher Chung (Apple Tv)