Twentysomething River Cartwright has a promising career in MI5 until a catastrophic error allows a terrorist attack to take place at King’s Cross. He is sent to Slough House (‘slow horse’), a nondescript office in east London where spy rejects end up. There it is made clear to them that they are out of the game, and will be kept busy doing the most menial ‘intelligence’ tasks until they quit: it is, in short, the government’s way of trying to get rid of failures and irritants without paying redundancy. River joins a team of alcoholics, arrogant tech geeks and nervous wrecks, all overseen by Jackson Lamb, the overweight boor who knows where all the bodies are buried. However, since they are all trained spooks it doesn’t take much for them to get their mojo back. A student is kidnapped in Leeds, with his threatened beheading to be broadcast online. But something about the whole thing doesn’t quite add up… As one reviewer puts it: ‘Think Le Carré with fewer posh people and laugh-out-loud funny.’ That’s a pretty reasonable summation, and Le Carré fans will recognise the internal intrigues, grubby power struggles and quiet warfare between individuals and departments within MI5 itself. Lamb himself is an irresistible creation. At one point he seems about to give a pep talk to his rag-tag crew: ‘”You’re fucking useless, the lot of you.” They waited for a “but”.’ Herron delights in language: ‘The shops opposite were a High Street palindrome – Korean grocery, courier service, lettings agents, courier service, Korean grocery’. He is dryly amusing, too. Of one politely fractious management meeting he says: ‘You had more chance of reaching a consensus with a vox pop on Marmite.’ He also has a nice line in incidental detail: the Mozart logo which signifies grade A-classified MI5 documents, for instance – and, winningly, the plastic transfer of birdshit covering a bench ‘in a twelve-yard corridor of CCTV limbo’ by the Globe Theatre so that no tourists sit on it, leaving it open for delicate MI5 meet-ups. This is the first of four Jackson Lamb books – so far – by Herron and, on the evidence of Slow Horses, the rest will be worth staking out.