Slow Horses season three review – Kristin Scott Thomas is absolutely top-notch

<span>Photograph: Jack English/Apple</span>
Photograph: Jack English/Apple

If you don’t know the sort of spy series that Slow Horses is by now, then the Bond-esque chase sequence through the streets of Istanbul that kicks off season three should set you straight. A woman is on her way to leak a mysterious, potentially world-changing secret document, pursued by an athletic man who is also her lover. It begins on foot then takes to the water, and it’s all high-end, big-budget excitement. And when they get into cars to drive through squeakily narrow streets, they do so not in classic sports cars or on sexy motorbikes, but in a sensible silver estate and a mucky little hatchback.

Slow Horses is all about the grubby glamour. After the fireworks of last season, we rejoin the least essential members of MI5 at Slough House, who all find themselves in various states of tedium. River (Jack Lowden), who really cannot catch a break, has returned to the drudgery of filing boxes stuffed with what is probably extremely insignificant paperwork, while Standish (Saskia Reeves) can only look on and tell him to stop moaning about it. Shirley and Louisa are (separately) trying to get drunk and hook up with random strangers; Ho and Marcus are doing their best to get in their way; and Kristin Scott Thomas does top-notch haughty, almost drolling herself into an early grave with world-weary lines like: “Just point me to the nearest exit.”

Gary Oldman as Jackson Lamb in season three of Slow Horses.
Gary Oldman as Jackson Lamb in season three of Slow Horses. Photograph: Jack English/Apple

And then there’s Lamb (Gary Oldman), whom we meet again as a farting, sleeping spectacle in the waiting room of an elite private doctor, where he offends the posh people around him with his general aura and stench. This is the Slow Horses way: the hero is a kebab-loving, chain-smoking, drunken slob who claims to be terrible at his job but is actually embarrassingly competent. Lamb is attending his compulsory service medical check, which leads to many delightful exchanges with his doctor about his drinking, smoking and exercise habits. “I’m a fucking titan,” Lamb decides.

It doesn’t take long before all these aimless spies find themselves in need of a thrilling, dramatic, spy-worthy problem to solve, and the long fallout from that mysterious chase around Istanbul seems as good a place as any to start. If the first episode gets most of its mileage out of jokes about how messy the Slow Horses are, it kicks into action when one of their own is kidnapped, and the others must band together to work out what is happening and how to fix it.

There is a bit of a paradox here, in that this is supposed to be about terrible spies. “You lot are about as much use as a paper condom,” says Lamb at one point, while the MI5 agents who are allowed into the official building still see them as the opposite of “proper fucking grownup spies”. But actually, the Slow Horses are all pretty good, even River, and it is the people spying on them who are in fact the bad spies.

Related: Gary Oldman: cinema’s master of disguise returns as Slow Horses’ seedy spook

Lamb is stalked through the streets of London by a man so cartoonish he would be less conspicuous if he were wearing a trenchcoat, monocle and fedora – though, as always, the way Lamb deals with him is casually spectacular. The only time I question Louisa’s judgment is when she is shocked that a coffee in London costs £3.50. “Do the coffee beans fly in first class?” she asks, which makes me think this was filmed in 2010. The two big names here, Oldman and Scott Thomas, are both Oscar-winning draws, but they lead the cast in the way that A-listers increasingly lead TV shows, which is to say that they aren’t always in it. Still, as Oscar-winning draws go, they are a very good pair to watch.

As always, Slow Horses is a pleasure. It’s big, bold and unapologetically daft. It wallows in the traditions of a regular spy drama like a pig in muck, throwing in a subplot (or is it?) about a single diamond, missing from the haul of season two. There are anonymous letters and secret meetings and those red dots that make it clear a sniper has a gun trained on someone. There are plenty of big twists and loads of chase sequences, even if they are carried out in vehicles that are more practical for the school run than high-stakes secret service stuff. Yet there’s a layer of self-deprecation that keeps it lively and fresh. It is funny and crude, but tense and gripping, and as such, it is a roundly entertaining, solid spy thriller.