Spoilers follow, obviously
Scars ends this series on a note that’s superficially positive but with enough ambiguity to make us uneasy. That’s where we should be at the end of a Slow Horses adventure. But this series has raised questions about what this show should really be about. Is it a series of spy thrillers? Should it be faithful to the source material? To what extent should there be story arcs and character development? These are the issues that have caused arguments and dissent online.
The novel series 5 is based on, London Rules, is a bit of an outlier among Mick Herron’s Slough House series. It’s farcical in its humour and pushes the idea of a realistic spy thriller to its limits. I’d almost argue that the book isn’t really about the horses but an exploration by Herron about power and ethics among politicians and the media. In the previous series/novel, the horses, let’s not forget, had their own premises stormed by a gunman who just happened to be the half-brother of one of them and who fatally shot a slow horse in the line of their duty. So it’s not that surprising that in the following adventure, they may not be at the top of their game.
Now we’ve got to the end of the season we can see the line walked by the TV producers. They’ve refocused a great deal of the humour which in the novel is expressed through the characters’ thoughts rather than through dialogue or action. They’ve also repurposed much of the plot, at the expense of the Gimballs and also Jaffrey who became a ridiculous figure, in order to emphasise the role of the slow horses. They’ve also given both Lamb and Catherine more screen time, the latter move made necessary by the departure of Louisa.
In the novel, the final scene sees Diana Taverner, rather than Whelan, travel to Slough House to have it out with Jackson. The evidence Jackson produces is quite different, but the ultimate effect is the same: Taverner will finally achieve the position of First Desk that she has coveted for so long. (It feels a bit like when Snape gets to be Defence Against the Dark Arts teacher at Hogwarts, and we feel just as uneasy.) But many of the lines of dialogue move from page to screen unchanged.
Probably the key scene in the whole series is when Shirley, Coe and River (‘my best agents…and you’) go to Abbotsford on Coe’s hunch. The bickering between Shirley and River as they attempt to get Jaffrey away from the terrorist is what series 5 is about. That Shirley of all people is the voice of reason almost overshadows the point that the horses have flashes of competence when they aren’t tripping each other up. It’s the tripping up that we’re here for, not the smooth defence of the realm and if the latter is what you’re into then I suggest you might be in the wrong place.
Speaking of in the wrong place, the rise and fall of Claude Whelan over the last couple of series has been quite spectacular. It was said of a particular football manager that he had ‘risen without trace’ and that phrase seems appropriate to Whelan. His effective moments seemed only to come when he decided to play a role of First Desk and when no operational or strategic nous was required. His experience with the escort (by the way, do we think there might have been a paid arrangement with the woman whom River meets at Whelan’s home?) and his swiftness to find common cause with Peter Judd are particular low points, and if he came to trust River for the simple and sound reason that River had saved his life (thus giving Cartwright jr a redemption that he hardly deserved), well, River was a fool for trusting that Whelan would write a cashable cheque. And if Whelan’s fall comes from the coincidental acquisition by Lamb of a now deceased politician’s Dictaphone, well, Whelan can have no complaints.
If, in series 1, we thought that Slow Horses was the River Cartwright show, Scars reminds us that it is very much Jackson’s. We have to ask whether Lamb has enjoyed himself a little more this time round. The door-knocking mime to Catherine was hilarious. But the simple ending shot, showing feet scarred back in Berlin, leaves us with a great deal to consider before series 6.
Cafethinking 
That simple bit of visual story telling with the feet was so powerful. Really using the medium well, complementing the kind of inner-monologue story telling Mick gets up to in the books perfectly. I’m sure the series has been left in safe hands for the future, but they’ll miss Will Smith’s genius for moments like this.