A couple of years ago, people I know were talking about the Apple TV series Slow Horses, the television version of Mick Herron’s Slough House novels. I love espionage novels, and I like espionage television series, too, but I can’t afford another streaming service — I have children on the cusp of university! — so I hadn’t seen any episodes of the series until I was flying in a plane. I watched three episodes (generously provided by the airline) and afterwards concluded that while the episodes were sweary, they were sweary in a reflexive, unaesthetic way, whereas the novels were full of clever and innovative swearing, and for that reason alone the books were more worth reading than the television show was worth watching.

Some authors and their audiences prefer their books clean of profanity, or they hide the profanity behind a fig-leaf of literary technique. We can have it both ways: we all know that the profanity is there, but we don’t have to own it, and we don’t have to behold it in all its glory. Other authors and readers, however, let it all hang out — they celebrate profanity and insinuate that, at least in telling some stories, profanity is essential language. Mick Herron’s series of spy novels, focused on the spies assigned to Slough House — spies who make big mistakes but can’t easily be fired, so are warehoused there until they’re killed or quit — revel in bad language, which is necessary to its comedy and to the development of character and narrative cohesion: in Herron’s case, at least, profanity is a term of art.