Slow Horses

Jackson Lamb's bitter running commentary is the thing the screen can only suggest. Gary Oldman gives you the belches and the insults from the outside. Herron's prose puts you inside Lamb's calculations, showing what he sees, what he is plotting and how little he thinks of almost everyone around him. That interior view changes how every scene with him reads. The book is also where the dialogue the show borrows so faithfully first appears, surrounded by narration that is just as sharp. Herron's omniscient voice drifts through London and into the heads of spies, bureaucrats and bystanders, and much of his dry humour lives in those asides rather than in anything a camera could film. It is also the first of the Slough House novels, published in 2010. On the page, Taverner and the Regent's Park power players stay further in the background, and the focus rests on the failed agents doing the work. Reading from the start gives you the series as Herron built it, before the show began combining and reshaping the later books.

Much of the dialogue in the first season comes straight off Mick Herron's pages, and the plot of Slow Horses follows the novel closely. Nothing reported suggests the ending was changed, so as far as is known the season is largely faithful to the book's conclusion. Herron has said season 1 tracked his plot closely, and that the bigger changes in later seasons were made with his agreement or at his suggestion. The changes in season 1 are mostly practical. A key sequence set at King's Cross in the novel moves to Stansted Airport, reportedly to give the directors more room. The final chase runs longer than on the page and adds both high drama and broad comedy. The larger shift is in who gets screen time. Diana Taverner is far more central and openly Machiavellian on screen, where the books keep her more distant and cautious. Claude Whelan, a bland figurehead who barely appears in the novels, becomes an insecure man out of his depth. David Cartwright's dementia arrives earlier and more directly, becoming a storyline from season 2, while the books let it build slowly and bring it forward mainly from Joe Country onward. Later seasons move further from the page. The show adapted one novel per season through season 5, then combined Joe Country and Slough House in season 6. That season changes how Sid Baker returns. In the novel she reappears while River is going about his normal life. On screen she turns up at his grandfather's house after the team has gone dark because former Slow Horses are being targeted. A producer has also said the character Reece was altered, though how is not clear. The one thing the show cannot do at all is get inside Jackson Lamb's head.