‘Slough House’ is dirty; ‘Spook Street’: deadly. Now we have the duplicity of ‘Joe Country’ – perhaps the next stop for Mick Herron’s ‘Slow Horses’ will be a devious ‘Intelligence Continent’?

As it is, ‘Joe Country’ is a fine addition to the series. Few writers can weave such deft description and pacy plotting – garnished with lashings of humour and even dashes of pathos – as Herron and each novel builds to a crescendo in which the reader is left feeling both traumatised and hungry for the next instalment.

There’s little doubt that Herron is a confident writer at the top of his game. This series has become famous for its openings: Dickensian wanders through locations in an omniscient voice quite unlike other writers working today. Here, he sheds this trope, instead opting for a reveal different to the structure of the other texts.

His confidence has also been apparent for a while in his wanton profligacy with his characters. It must take iron nerves for a writer to dispose of such well-rounded, independent characters brimming with such vim and spark as these Slow Horses. And yet, here again, Herron is prepared to dispose of them with abandon. As in the old TV series Spooks (MI:5 in the US), no one is safe and this means no reader can ever truly relax that their favourite character won’t end up at the knackers yard in the next ten pages.

Finally, there is Jackson Lamb. A Rabelaisian grotesque, becoming progressively more grotesque by the novel. And, in truth, Lamb is actually my biggest quibble of this first rate book. He dominates the proceedings so completely that you pine for his nastiness when he is off stage. This is Banquo as central character, relegating Macbeth to bit part player by sheer force of personality (or blackened toe wiggling through undarned sock, if you will).

There are a few minor worries deriving from Lamb which I hope are me being hyper critical. He keeps “appearing” and “vanishing” like an obese Paul Daniels – or a less creepy David Blaine – and I hope this doesn’t signal either Lamb as supernatural entity or that Herron is now so successful that he has entered the realm of the uneditable: too grand for repetitions to be noted and corrected. I think not on the whole.

‘Joe Country’ is proof, if any were needed, that Herron stands at the pinnacle of the espionage genre, (possibly snug on the heights with Jeremy Duns and Charles Cumming). Others have already noted it is not a book which would reward readers unfamiliar with the series but for all that, I hope the Slow Horses have many more races left to run.

In short: Horses far from in need of the knacker’s yard: 4/5*

• Other details:
• ISBN: 9781473660359
• Publication date: 20 Jun 2019
• Imprint: John Murray

Thanks to Netgalley for the advance copy