Slow Horses: high drama and comedy abound in this gripping spy thriller about reject spooks

The slow horses are a group of MI5 rejects who have been condemned to Slough House (their name a pun on the building they work in) after messing up, but not enough to get fired. Here, this group of misfits grind though dull administrative tasks under the occasional verbal abuse of their boss Jackson Lamb (Gary Oldman).

The quick-witted spy thriller is back for its fourth season following this crew of pencil pushers as they manage to get involved in stopping plots that endanger Britain.

Mick Herron, the author of the Slough House series of novels, has been described as the modern John Le Carré. Le Carré (real name David Cornwell) was a former intelligence officer and the premier spy fiction writer of the Cold War and post-Cold war era. But the connection is unfair to both Herron and LeCarré.

What they have in common is an antipathy to government intelligence agencies, and those who run them. They are both also sharp observers of character: of trust, of love and affection shown in odd ways and of betrayal.

Herron, however, is not attempting to portray the real business of intelligence. After all, the programme insists on calling officers agents throughout. Herron is more concerned with complex and interesting characters and plot. The spying is just the pivot. The one intelligence truism he does hit upon though, through his deputy director general of MI5, Diana Taverner (Kristin Scott Thomas), is: “never stress the frailty of human intelligence”.

The frailty of the human condition is very much on show in Slow Horses, and Slough House is full of it. The characters are all damaged in some way and the question of whether a spy can ever rejoin mainstream society sits uneasily over the series.

Boss Jackson Lamb is still somehow ahead of the game. Freed from his desk, he’s in the field alert to twists, while looking more shambolic than ever – there are holes in his socks and his drinking problem is out of control. After being kidnapped last season, British intelligence administrator and former alcoholic Catherine Standish seems freed from her addictions and seeking to be freed from intelligence work – I suspect, however, she will still feature in future series.

The disgraced junior agent River Cartwright (Jack Lowden), who is the main focus of this series ends up the centre of the major plot twist, which clarifies his familial connection to MI5. Amidst his usual heroics he also tries to draw attention to his grandfather’s, David Cartwright (Jonathan Pryce), worsening dementia.

The treatment of the retired senior MI5 officer shows the fracture between intelligence officers and the people they ultimately serve. The final scenes will tug at the heart of anyone who has a relative with dementia.

There are also new faces in Slough House, including JK Coe. Coe rarely says anything but when he jumps into action he seems to have the sharpest instincts. Coe is in Slough House because of his PTSD. He is the bridge to our modern world with his very occasionally revealed emotional intelligence. As an expert in intelligence, Coe is one of the only characters I could actually see in MI5 – once he recovers, of course. Also new is Emma Flyte (Ruth Bradley) who has left the Metropolitan Police because no one could tell her the truth. MI5 turns out to be more of the same.

Bubbling across the series is a story of female exploitation and misplaced male heroism which has huge negative consequences.

The female officers at Slough House consistently show themselves to be the more effective of the troupe, but they are the ones that most often face the barbs and “banter”. Lamb, we are led to believe, has a heart of gold and despite his frequent abuse, cares for them all deeply. However, it requires a lot of generosity to believe this.

The top of MI5 also seems to struggle with gender as we are introduced to newly promoted Claude Whelan who has grabbed first desk (director general of MI5) from Diana Taverner. Whelan sets out to shine the light of transparency on intelligence (“my brief is to activate accountability and accessibility: that’s the triple-A promise”) but is ultimately a weak and flawed man. Diana Taverner is, however, a capable second desk (operational lead). She gets things done, makes brutal decisions, of which there are many in a series packed with drama.

Herron and Will Smith (who has written the TV adaptation) have gone overboard this series with drawing in news stories viewers will recognise. There is a bombing of a large shopping centre (a common plot), and there is a version of the murder of journalist Jamal Khashogi. There are unspecified untouchable foreign princes operating in London, cults and female exploitation. There is also the use of ghost identities (real identities of dead babies kept alive for intelligence purposes), which is a live issue at the ongoing Undercover Policing Inquiry.

Split over six, 45 minute episodes, the pace of the story telling is relentless and the episodes just fly by. The show thrives in its balance between the humorous interplay between the reject inhabitants of Slough House (think the wry comedy of The Office) and the jaw-dropping plot twists. Balancing complex drama and clever comedy is difficult but perfectly executed here.

Slow Horses remains, in my opinion, the best that television drama has to offer at the moment.

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Robert Dover does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.