Slow Horses season six review – it gets harder to enjoy Gary Oldman’s spy thriller every year

The show’s creator has gone, it’s been retooled as a conventional thriller and it feels like it’s starting to run out of ideas – even if it’s as slick and confident as ever This is a new Slow Horses: season six is the first not to be guided by Will Smith, a writer whose previous work on The Thick of It and Veep explained why this espionage saga had an unusually sharp comic tongue.

The absence of Smith’s drollery is discernible in a more straight-faced new story, but the bigger problem is one of a creative work naturally eroding over time. Slow Horses is now old. It’s always been a difficult, delicate proposition. The staff of Slough House, a purgatorial spin-off of MI5 where misfits and screw-ups are given boring work when it would make more sense to just fire them, regularly outstrip supposedly elite spies despite being shambling losers. Leading the field agents is River Cartwright (Jack Lowden), who has the good looks of a spy hero and…