Russian thugs, a shootout and a svelte supervillainess... this finale had it all: CHRISTOPHER STEVENS reviews Slow Horses

Slow Horses (Apple TV)

Rating: Four out of five stars  

Moscow Rules, declared unit chief Jackson Lamb in the finale of Slow Horses. 

It's a phrase to send a thrill of recognition through the blood of every classic spy tale aficionado.

George Smiley, the mild-mannered hero of John le Carré's 'Circus' novels, invoked Moscow Rules repeatedly. 

Developed by the CIA, these were the core principles of tradecraft, the tricks Cold War agents practised to avoid breaking cover.

Top of the list were 'Assume nothing' and 'Never go against your gut'. 

Unluckily for Lamb (Gary Oldman), none of his 'joes' – the hapless failures and klutzes under his command – would recognise a gut feeling if it came with two Alka-Seltzer and a spoonful of bicarb.

The fun of Slow Horses is that it pretends to be an anti-spy story, while simultaneously satisfying all our cravings for a traditional espionage adventure. 

This climactic episode delivered everything: a delicious double cross, Russian thugs, a svelte supervillainess and a bloody shootout at a safe house.

But it also subverted all the cliches. 

Every James Bond fan will enjoy the reference to Thunderball, when Shirley (Aimee-Ffion Edwards) – the grumpiest and least incompetent of Lamb's proteges – discovered a loaded harpoon gun in the bottom of a rowing boat on a Suffolk beach (What was it doing there? Don't ask, doesn't matter).

But she didn't get to fire it. That honour went to Reece, played by Lenny Rush, who is just under 3ft 3in and possibly the worst Sean Connery lookalike of all time.

Kristin Scott Thomas, who plays the head of MI5 Diana Taverner, wouldn't look out of place as M in a 007 movie.

But she had to hold her nose, almost literally, as she slid into the passenger seat of Lamb's car... which definitely isn't an Aston Martin. I'm not sure but, beneath the rust, I suspect it's a 1990s Honda.

Taverner had been double-dealing with the Russians. 'I'd think twice before admitting to treason,' Lamb advised her. 

'That's your pension f****d right there.' Under all that gunge beats the heart of an old-fashioned civil servant.

Every series of Slow Horses follows the same pattern: Lamb despairs of his useless agents, they strive for his approval but foul everything up, and he is eventually obliged, against all his better instincts, to save their skins... or at least the ones who are not dead. 

This season, the body count has been unusually high.

Despite the grottiness of the Slow Horses HQ and Lamb's stomach-turning personal habits, this show is often beautifully filmic. 

One aerial shot revealed blue dots converging on a green background, like a piece of liquid modern art. They turned out to be armed guards on an airstrip.

I'm puzzled, though, that the windows in the coastal safe house were all blown out during a gunfight, yet seemed intact again by the time MI5 reinforcements arrived. Double glazing salesmen in Suffolk must work fast.