‘Slough House’ is my seventh visit with the British Security Service screwups who have been exiled from the shining high-tech HQ to the grimy dilapidation of Slough House where they live lives of demoralising drudgery, doing nugatory work for the irascible Jackson Lamb. Yet somehow, in book after book, Mick Herron finds highly plausible ways of putting these screwups in the cross-hairs of dangerous enemies. Mick Herron is not kind to his characters. He never gifts them glory, barely grants them a tolerable existence and never hesitates to kill one or two of them off if the plot requires it.

If you haven’t read any of the other Slough House books, don’t start here. Mick Herron doesn’t do ‘previously, on Slough House’ passages. He expects his readers to be up to speed on who did what to whom and why. Go back to ‘Slow Horses’ and savour the six books before this one.

The Slough House series is at a point where it is carried along by the momentum of its own history. Its path is set by the guardrails of contemporary politics, seen from the inside with the blinkers off, and kept human by the focus on the people who have become by now much more than a cast of characters.

Mick Herron pulls no punches when it comes to describing the mechanics of British politics and the (largely internal) threats to democracy. In this instalment, events are driven by the ambition of an Old Etonian using foreign money and clickbait media to subvert democracy to gain personal power. Think of him as Boris Johnson’s cleverer elder brother. The political dynamic is depressingly plausible and beautifully described.

An unintended but not unwelcome consequence of the Tory Monster’s scheming is that the occupants of Slough House find themselves targeted by an enemy power. This provides the opportunity to weave tense, violent action between the political plotting and once again puts the lives of the Slough House folks at risk.

While the plots of Herron’s novels fit together with a precision that is satisfying to watch, what keeps me coming back is the quality of the writing and the depth of the characterisation. We see the world from the point of view of multiple characters and each time we learn as much about the characters themselves as we do about the next step in the plot. Herron’s writing moves seamlessly from the lyrical to the cinematic and effortlessly strings individual perspectives onto his narrative thread like pearls catching the light.

I admire the fact that all of Herron’s characters are flawed and some of them are almost completely broken and yet he makes me care about what happens to them, even the truly dislikable ones like Jackson Lamb, who I would hate to meet in person.

I recommend the audiobook version of the book. Sean Barrett’s narration is more like a one-man show. He has developed the voices of the main characters so clearly that you know who’s talking as soon as they open their mouths. He also delivers the authorial voice in a way that brings out the acid humour and the abstract thoughts with equal confidence.