Gary Oldman’s Jackson Lamb Faces His Most Dangerous Mission Yet in Slow Horses Season 6

Jackson Lamb may be the foul-mouthed, disheveled boss of MI5’s Slough House, but beneath the dirty raincoat and constant insults lies one of the agency’s sharpest minds. In Slow Horses Season 6, that intelligence is put to the test when his team becomes the target of a dangerous game of retaliation and revenge.

Gary Oldman, who has earned three Emmy nominations for his portrayal of Lamb, including one this year, says the character is not someone who readily shows emotion. As the head of Slough House, Lamb treats vulnerability as something he simply cannot afford.

Yet beneath his abrasive exterior, there is a fierce loyalty to the agents he constantly humiliates.

“He would take a bullet for them,” Oldman says. And once Lamb realizes his “joes” are genuinely in danger, he takes matters into his own hands, determined to understand why they have been targeted and who is behind it.

Jackson Lamb’s greatest weapon may be being underestimated

Part of Lamb’s appeal comes from the contradiction at the heart of his character. He looks like someone nobody should take seriously, right down to the battered raincoat he wears almost like protective armor.

Oldman describes that appearance as both a disguise and a deliberate part of Lamb’s skill. People see the shabby clothes and unpleasant personality and assume they already understand him. That is precisely where they make their mistake.

The actor and executive producer has compared Lamb to Peter Falk’s iconic detective Columbo, another character frequently underestimated by the people around him.

“They all miscalculate him,” Oldman says, pointing out that Columbo ultimately proves himself to be the smartest person in the room. In his view, Jackson Lamb operates in much the same way.

That quality becomes particularly important in Season 6, when Lamb’s team is no longer simply dealing with the usual dangers of intelligence work. They are being actively targeted, forcing their seemingly reluctant leader to step forward.

Slough House is pushed into a deadly game

Based on Mick Herron’s novels, Slow Horses has built its reputation around dark humor, sharp writing and a cast that includes Kristin Scott Thomas, Jack Lowden, Saskia Reeves, Christopher Chung and Jonathan Pryce.

The series has also maintained an unusually consistent release schedule. Each season contains six episodes, with new seasons arriving every year since 2022, including two seasons released in its first year. The seventh season has already been filmed.

Season 6 marks the first time the series has combined material from two of Herron’s novels: Joe Country and Slough House.

Gaby Chiappe, who takes over as lead writer from Will Smith, says bringing the two stories together “made complete sense.” She has been careful not to reveal too much about the new season, but one major development is clear: the members of Slough House have to disappear from view after Diana Taverner, MI5’s First Desk, draws them into a high-stakes conflict driven by revenge and retaliation.

That puts Lamb and his team in an increasingly precarious position.

And, as Chiappe warns, the danger this time is not simply an illusion.

Lamb and Taverner remain a formidable pairing

Season 6 also brings another round of confrontations between Lamb and Diana Taverner, played by Kristin Scott Thomas.

Oldman clearly enjoys their scenes together, joking about Taverner’s supposedly “lovely and charming” personality. He and Scott Thomas previously worked together in The Darkest Hour in 2017, and the opportunity to reunite has been a welcome one.

For Chiappe, the appeal lies in how effectively the two characters work against each other. Their history means neither is likely to trust the other, but that does not prevent a strange relationship from developing between them.

There is, she says, a “weird, twisted camaraderie” beneath their constant tension.

That relationship could become even more important as the stakes rise. Chiappe offers one particularly ominous warning about Season 6: “No one is safe.”

When the characters are in danger, she says, the threat is genuine — and sometimes people die.

Sid Baker returns

One of the season’s biggest surprises involves Olivia Cooke’s Sid Baker.

Sid was placed in Slough House by Taverner during Season 1 to spy on River Cartwright, played by Jack Lowden. She appeared to die after being shot in the head while on an assignment.

Now, she is returning for Season 6.

Chiappe is particularly enthusiastic about bringing Sid back, calling the character “brilliant” and pointing to the chemistry she shared with River during the first season.

Their connection left an impression, and the writer hopes viewers will once again become interested in where that relationship could lead.

River Cartwright and Frank Harkness face unfinished business

Hugo Weaving is also returning as Frank Harkness, the mercenary and former CIA operative who is also River’s father.

Their relationship has never been simple. Harkness has previously tried to kill his own son, making every encounter between them inherently volatile.

According to Chiappe, both Weaving and Lowden wanted to take that dynamic further in Season 6.

The new season explores what it means for Harkness to have created a son essentially to become a soldier, only to lose him. It also asks what it means for River to have a father like that.

Harkness might insist that River means nothing to him, but Chiappe says that interpretation does not fully match what viewers have seen. There is something else there — an interest in his son that may even resemble a twisted form of pride, although she considers “pride” too strong a word.

A new face changes the Slough House dynamic

Comedian Lenny Rush joins the cast for Season 6, although details about his character are being kept secret.

What Chiappe will reveal is that he is a teenager, making him the first character of his age to enter the world of Slow Horses.

His presence creates an unexpected dynamic within Slough House, particularly when he is paired with Jackson Lamb.

Chiappe describes Lamb and the teenager as an “odd couple,” and says watching that relationship develop is one of the season’s most satisfying elements.

The slow horses are carrying the weight of their past

As the series moves into its sixth season, the damage caused by years of espionage is becoming increasingly visible.

The characters have experienced deaths, losses and grief, and Chiappe says everyone is beginning to carry the consequences of what they have endured.

“Everybody’s picking up damage,” she notes.

That accumulated pain is part of what gives Slow Horses its emotional weight. These agents may be dismissed as MI5 rejects, but the series has gradually turned them into a group whose loyalty to one another matters just as much as their professional survival.

Lamb himself would never put it that way.

“I think they’re a bunch of f**king losers. But they’re my losers.”

And that may be the simplest explanation for why Jackson Lamb will not sit back while his team is hunted.

** Slow Horses Season 6 premieres Wednesday, September 16, on Apple TV.**