All the clues you might have missed about Line of Duty's H / The Fourth Man

Yes, recurring character DSU Ian Buckells (played by Nigel Boyle) was at last unmasked as the corrupt cop pulling strings on behalf of organised crime. Once erroneously code-named H, latterly known as the Fourth Man and now forever associated with baffled cries of: “What the… Buckells? Are you sure? Yes but Buckells, though? Mother of God!”

Despite fan theories proliferating online, bookmakers taking bets and everyone having their own pet theory, the big Buckells reveal miraculously managed to still pull off a major surprise. But has writer Jed Mercurio been laying a nine-year, six-series trail of subtle hints all along?

Let’s look back through Buckells’ Line Of Duty journey for clues, examining what he did and how he got away with it for so long…

Pre-series 1: Falling in with a bad crowd

The first we knew of Buckells’ police career was when he was a young Detective Constable on the team investigating the racially motivated April 2003 murder of Lawrence Christopher - one of the shameful scandals being probed by assassinated journalist Gail Vella (Andi Osho).

His commanding officers were confirmed bent copper™ DCI Marcus Thurwell (Jimmy Nesbitt) and then-Inspector Philip Osborne (Owen Teale), also a strongly suspected wrong 'un. Their inquiry was a litany of blunders: wrongly assuming the attack was gang-related, failing to follow up on tip-offs or secure forensic evidence, slow progress allowing time for the five suspects to shave their heads and avoid identification. A flimsy case meant they were all released without charge.

The investigation was deliberately sabotaged by Thurwell to protect one of the ringleaders: Darren Hunter, son of organised crime kingpin Tommy Hunter (Brian McCardie). Buckells seems to have been indoctrinated into such malfeasance from an early stage of his career and doubtless had his head turned by the dirty money involved.

It’s hinted that Buckells was recruited to the shady squad through his Masonic connections. Membership of the Freemasons is always a red flag in Line Of Duty, hinting at corruption and collusion. See the secret handshake between Supt Ted Hastings (Adrian Dunbar) and retired Chief Supt Patrick Fairbank (George Costigan) in series three. This enabled Ted to later be accused of both corruption and sexism, while Fairbank was convicted for child sex abuse. Nice company Buckells was keeping, with his Britpop haircut and taste for the high life.

Series 1: Bent friends in high places

By the debut series in 2012, Buckells had ascended to Detective Inspector at Kingsgate Station. He was assigned to look into Jackie Laverty’s disappearance by none other than CSU Derek Hilton (Paul Higgins), who was unmasked in series four as the highest-ranking corrupt officer affiliated with the OCG. The pair were on chummy first-name terms.

As part of his typically fruitless inquiry, Buckells interviewed Ryan Pilkington (Gregory Piper) when he was still a gobby OCG errand boy, delivering drugs and burner phones on his BMX. So Buckells surely knew that the grown-up PC Pilkington was a gangland mole in series six. Indeed, his decision not to charge Ryan kept his criminal record clean, meaning he was later able to pass background checks and join the force as the OCG’s inside man.

There was a telling exchange when Laverty’s lover, DCI Tony Gates (Lennie James), spoke to Buckells about Laverty laundering money for organised crime. Gates asked: “What do you know about financial irregularities?” Buckells gave a sly smile and replied: “Enough.”

He also enabled a clandestine conflab between DS Matthew “Dot” Cottan (Craig Parkinson), aka The Caddy, and OCG boss Tommy Hunter following his arrest in the series one finale. His excuse was that Cottan’s enquiries related to Counter Terrorism but the private chat actually enabled Cottan to advise Hunter to enter witness protection.

Buckells even bantered proudly with his corrupt colleague remarking that Cottan won’t be calling him "Sir" for long, having heard he was due to take the Inspector's exams. “Congratulations, Dot,” he grinned. How cosy.

Off-screen, series 2 and 3: Failing upwards

Buckells was promoted four times during his 16-year career in Central Police - his climb through the ranks enabled by fellow crooked officers.

While he didn’t appear on-screen during series two and three, he was busy lining his pockets and becoming a Detective Chief Inspector. Writer Jed Mercurio seems to be suggesting that elevating incompetence is almost as dangerous as active corruption. Buckells was guilty of both.

Series 4: Hostility to AC-12

Buckells reappeared as the replacement for DCI Roz Huntley (Thandie Newton) when she was removed as head of Operation Trapdoor. He spotted the presence of DS Kate Fleming (Vicky McClure) on the team, having first encountered her in series one, and correctly surmised that she was working undercover for anti-corruption. Not good news for Buckells, who was up to his neck in it.

Hastings had a shady night-time meeting with Buckells in an alleyway, ordering him not to blow Kate’s cover. Buckells reluctantly agreed but made no secret of the fact that he didn't want to assist, refusing to give Fleming intel on a meeting she'd been excluded from because he was "no grass.”

When Kate was eventually unmasked, Buckells denied giving her up but once again made his disdain for AC-12 plain. He was angrily dismissed by Hastings but not before remarking: "You lot treat everyone like mugs. Who's the mug now?” – phrasing which would resurface in the series six finale.

When Polk Avenue Station staff met at a local pub after work, Buckells behaved awkwardly when asked to get his round in - hence Fleming’s dig at his tight-fistedness.

Buckells was also visited by old pal Hilton, now Assistant Chief Constable. In a private meeting, the pair shared relief at the "small mercy" that they were now able to refer to Operation Trapdoor victims as “prostitutes”, which Huntley had expressly prohibited when she was leading the case. Again, a cosy corrupt boys’ club.

Off-screen, series 5: The Fourth Man arrives

Once more, Buckells was busy getting promoted while off-screen, this time to Detective Superintendent. This was also the series when the “Fourth Man” theory was born, after Cottan’s dying declaration was ret-conned to implicate a quartet of bent high-ranking officers.

AC-12 had caught three of them: Cottan, ACC Hilton and police lawyer Gill Biggeloe (Polly Walker). However, the fourth and final corrupt copper remained at large. While viewers were all looking suspiciously at Hastings, Buckells carried on his bent business.

Series 6, episode 1: That crucial delay

When we were reacquainted with DSU Buckells in the latest series, he was somehow heading the Murder Investigation Team at Hillside Lane Station. As the boss of DCI Jo Davidson (Kelly Macdonald), he oversaw Operation Lighthouse, the unsolved murder of Gail Vella.

Davidson appeared to be the one at fault for delaying the arrest of suspect “Ross Turner” but Buckells played his part too. It was him who expressed doubt about the reliability of the CHIS tip-off and suggested they wait until the next morning for executive level sign-off. Hastings accused him of “decision-dodging” when it was actually more calculated.

Buckells knowingly allowed Davidson to put through the wrong surveillance paperwork, hiding his culpability behind a smokescreen of clumsiness. She thought she was manipulating him, but the reverse was true. Remember all those furtive looks from Buckells through the glass into Davidson’s office? He was watching her, rather than the other way around.

He pushed for the arrest of Terry Boyle (Tommy Jessop) because it fitted the “lone stalker” theory and led the investigation away from OCG involvement, justifying this as a hunger for results to impress his superiors. Buckells also pulled strings to disclose the identity of the CHIS, rent boy Alastair Oldroyd, who could confirm whether Terry was the mystery man bragging about Vella’s murder. Oldroyd was soon found dead. Buckells had blood on his faux-bumbling hands.

Series 6, episode 2: Golfing giveaway

Ever since Tommy Hunter was apprehended at Edge Park Golf Club, the sport has been synonymous with organised crime in Line Of Duty’s fictional universe. After all, Cottan got his “Caddy” nickname because he was groomed while carrying Hunter’s clubs.

It was an ominous sign early in series six when viewers spotted a golf bag stashed in the corner of Buckells’ office - not to mention framed photos of himself out on the fairways and greens. Golf clubs were later spotted in the boot of his car, alongside the missing Operation Lighthouse case files. Fore! Bent copper incoming!

Series 6, episode 3: Jobs for the boys

Buckells was swift to put forward probationary PC Ryan Pilkington for a commendation after the reservoir car crash, realising that such recognition would help fellow bent copper Ryan to climb through the ranks.

When Fleming credited Davidson for bringing Pilkington onto the team, she replied: “Not me, that was Buckells’ idea. Family friend or something. Probably got a nudge down at the Masonic lodge.” Those Freemasonry connections again, along with a reminder that he knew full well who Ryan was.

Series 6, episode 3: Caught but only temporarily

The third episode also saw Buckells arrested for his actions surrounding Operation Lighthouse – including those missing files and his links with Deborah Devereaux, a “witness” who owed him a favour after he got her off an assault charge years previously. She implicated Terry Boyle in what was clearly a false statement.

Few fans really believed that Buckells was in league with organised crime, instead buying into the idea that he’d been set up by Davidson. “Buckells couldn't run a bath, let alone an OCG,” as one viewer tweeted. Yet this was precisely what he wanted us to believe.

Davidson promptly went home, opened her laptop and typed into that secret online messaging service: “All under control now.” The mysterious “Unknown User” didn’t reply - but that’s because he was in AC-12 custody at the time.

• For the latest news and expert tips on getting the best deals this year, take a look at our Black Friday 2021 and Cyber Monday 2021 guides.

Series 6, episode 4: Wolf in sheep’s clothing

In the first of his two AC-12 interviews this series, Buckells was confronted with evidence of his involvement in the deaths of hitman Carl Banks, informant Alastair Oldroyd and drowned PC Lisa Patel - plus the failure of Operation Lighthouse, upon which he was the longest serving officer.

Once again, it looked to be ineptitude rather than incompetence (“I don’t know why I don’t know”). This illusion enabled him to hide in plain sight. Arnott didn’t believe Buckells could “organise a piss-up in a brewery” but Fleming foreshadowed the truth: “Yeah but that’s his cover.”

Sent to HMP Blackthorn, Buckwells distracted bent lawyer Jimmy Lakewell (Patrick Baladi) before OCG thug Lee Banks (Alastair Natkiel) garrotted him. We assumed this was simply a warning to Buckells but he was more complicit than he first appeared. The fact that he was visibly shaken was because he normally insulates himself from OCG violence, always several steps removed from the actions he helps orchestrate.

Despite Buckells’ weak defence against AC-12’s accusations, DCS Patricia Carmichael (Anna Maxwell Martin) deemed the case wasn’t watertight and dropped the charges against him. That hapless act had proved effective once again.

When the “Unknown User” fired up his messaging service again, he railed against AC-12 and ordered Davidson to “get rid of” Fleming. A move which wasn’t just expedient but the culmination of Buckells’ long-held hostility towards AC-12 and Kate in particular, who’d been a thorn in his side since series one. This time, it was personal.

Series 6, episode 7: Keyser Soze moment

Even during his climactic interview, Buckells kept up the act. He hid behind baffled looks, exasperated eye-rolls and tight-lipped “No comment”s. The mask only slipped when Hastings baited him with talk of “corruption hidden by incompetence” and being a “blundering fool”. Suddenly puffing up with arrogance, Buckells sneered: “Yeah right. I’m a blundering fool? I’m only the one who’s made total mugs out of you lot.”

Beneath the surface image of “crap suits and dad cars”, Buckells was leading a double life. He had a £3m property portfolio and bank accounts registered in the Cayman Islands.

AC-12 had tried to embarrass him about exchanging sexts with witnesses and suspects, but Buckells was unrepentant. “The big house, the fast cars, the bits on the side - is that what turned your head?”demanded Hastings. “Over the years, we’ve investigated all manner of motives but the basest, most mundane of all is plain, simple greed.”

• For the latest news and expert tips on getting the best deals this year, take a look at our Black Friday 2021 and Cyber Monday 2021 guides.

Buckells wasn’t a criminal mastermind. He was merely a middle man who accidentally rose through the ranks, did whatever he was asked to if the price was right, and ended up as the last bent copper standing. An unspectacular but all too plausible portrayal of the insidious nature of institutionalised corruption.

We ended with him in line for immunity and giving a self-satisfied smirk. If only Buckells could learn to spell “definately” correctly, he might still be at large. As a Scooby Doo villain might say: I would have gotten away with it too, if it wasn’t for those pesky typos.

Line of Duty season 6 is available on BBC iPlayer now, and we have all the latest news on Line of Duty season 7. Check out the rest of our Drama coverage, or take a look at our TV guide to find out what else is on.By: Michael Hogan

Did you hear that mass scream from sofas nationwide at around 9:34pm on Sunday? It was the sound of millions of blindsided Line Of Duty viewers exclaiming a single word. And that word was “Buckells?!”.

Yes, recurring character DSU Ian Buckells (played by Nigel Boyle) was at last unmasked as the corrupt cop pulling strings on behalf of organised crime. Once erroneously code-named H, latterly known as the Fourth Man and now forever associated with baffled cries of: “What the… Buckells? Are you sure? Yes but Buckells, though? Mother of God!”

Despite fan theories proliferating online, bookmakers taking bets and everyone having their own pet theory, the big Buckells reveal miraculously managed to still pull off a major surprise. But has writer Jed Mercurio been laying a nine-year, six-series trail of subtle hints all along?

Let’s look back through Buckells’ Line Of Duty journey for clues, examining what he did and how he got away with it for so long…

Pre-series 1: Falling in with a bad crowd

The first we knew of Buckells’ police career was when he was a young Detective Constable on the team investigating the racially motivated April 2003 murder of Lawrence Christopher - one of the shameful scandals being probed by assassinated journalist Gail Vella (Andi Osho).

His commanding officers were confirmed bent copper™ DCI Marcus Thurwell (Jimmy Nesbitt) and then-Inspector Philip Osborne (Owen Teale), also a strongly suspected wrong 'un. Their inquiry was a litany of blunders: wrongly assuming the attack was gang-related, failing to follow up on tip-offs or secure forensic evidence, slow progress allowing time for the five suspects to shave their heads and avoid identification. A flimsy case meant they were all released without charge.

The investigation was deliberately sabotaged by Thurwell to protect one of the ringleaders: Darren Hunter, son of organised crime kingpin Tommy Hunter (Brian McCardie). Buckells seems to have been indoctrinated into such malfeasance from an early stage of his career and doubtless had his head turned by the dirty money involved.

It’s hinted that Buckells was recruited to the shady squad through his Masonic connections. Membership of the Freemasons is always a red flag in Line Of Duty, hinting at corruption and collusion. See the secret handshake between Supt Ted Hastings (Adrian Dunbar) and retired Chief Supt Patrick Fairbank (George Costigan) in series three. This enabled Ted to later be accused of both corruption and sexism, while Fairbank was convicted for child sex abuse. Nice company Buckells was keeping, with his Britpop haircut and taste for the high life.

Series 1: Bent friends in high places

By the debut series in 2012, Buckells had ascended to Detective Inspector at Kingsgate Station. He was assigned to look into Jackie Laverty’s disappearance by none other than CSU Derek Hilton (Paul Higgins), who was unmasked in series four as the highest-ranking corrupt officer affiliated with the OCG. The pair were on chummy first-name terms.

As part of his typically fruitless inquiry, Buckells interviewed Ryan Pilkington (Gregory Piper) when he was still a gobby OCG errand boy, delivering drugs and burner phones on his BMX. So Buckells surely knew that the grown-up PC Pilkington was a gangland mole in series six. Indeed, his decision not to charge Ryan kept his criminal record clean, meaning he was later able to pass background checks and join the force as the OCG’s inside man.

There was a telling exchange when Laverty’s lover, DCI Tony Gates (Lennie James), spoke to Buckells about Laverty laundering money for organised crime. Gates asked: “What do you know about financial irregularities?” Buckells gave a sly smile and replied: “Enough.”

He also enabled a clandestine conflab between DS Matthew “Dot” Cottan (Craig Parkinson), aka The Caddy, and OCG boss Tommy Hunter following his arrest in the series one finale. His excuse was that Cottan’s enquiries related to Counter Terrorism but the private chat actually enabled Cottan to advise Hunter to enter witness protection.

Buckells even bantered proudly with his corrupt colleague remarking that Cottan won’t be calling him "Sir" for long, having heard he was due to take the Inspector's exams. “Congratulations, Dot,” he grinned. How cosy.

Off-screen, series 2 and 3: Failing upwards

Buckells was promoted four times during his 16-year career in Central Police - his climb through the ranks enabled by fellow crooked officers.

While he didn’t appear on-screen during series two and three, he was busy lining his pockets and becoming a Detective Chief Inspector. Writer Jed Mercurio seems to be suggesting that elevating incompetence is almost as dangerous as active corruption. Buckells was guilty of both.

Series 4: Hostility to AC-12

Buckells reappeared as the replacement for DCI Roz Huntley (Thandie Newton) when she was removed as head of Operation Trapdoor. He spotted the presence of DS Kate Fleming (Vicky McClure) on the team, having first encountered her in series one, and correctly surmised that she was working undercover for anti-corruption. Not good news for Buckells, who was up to his neck in it.

Hastings had a shady night-time meeting with Buckells in an alleyway, ordering him not to blow Kate’s cover. Buckells reluctantly agreed but made no secret of the fact that he didn't want to assist, refusing to give Fleming intel on a meeting she'd been excluded from because he was "no grass.”

When Kate was eventually unmasked, Buckells denied giving her up but once again made his disdain for AC-12 plain. He was angrily dismissed by Hastings but not before remarking: "You lot treat everyone like mugs. Who's the mug now?” – phrasing which would resurface in the series six finale.

When Polk Avenue Station staff met at a local pub after work, Buckells behaved awkwardly when asked to get his round in - hence Fleming’s dig at his tight-fistedness.

Buckells was also visited by old pal Hilton, now Assistant Chief Constable. In a private meeting, the pair shared relief at the "small mercy" that they were now able to refer to Operation Trapdoor victims as “prostitutes”, which Huntley had expressly prohibited when she was leading the case. Again, a cosy corrupt boys’ club.

Off-screen, series 5: The Fourth Man arrives

Once more, Buckells was busy getting promoted while off-screen, this time to Detective Superintendent. This was also the series when the “Fourth Man” theory was born, after Cottan’s dying declaration was ret-conned to implicate a quartet of bent high-ranking officers.

AC-12 had caught three of them: Cottan, ACC Hilton and police lawyer Gill Biggeloe (Polly Walker). However, the fourth and final corrupt copper remained at large. While viewers were all looking suspiciously at Hastings, Buckells carried on his bent business.

Series 6, episode 1: That crucial delay

When we were reacquainted with DSU Buckells in the latest series, he was somehow heading the Murder Investigation Team at Hillside Lane Station. As the boss of DCI Jo Davidson (Kelly Macdonald), he oversaw Operation Lighthouse, the unsolved murder of Gail Vella.

Davidson appeared to be the one at fault for delaying the arrest of suspect “Ross Turner” but Buckells played his part too. It was him who expressed doubt about the reliability of the CHIS tip-off and suggested they wait until the next morning for executive level sign-off. Hastings accused him of “decision-dodging” when it was actually more calculated.

Buckells knowingly allowed Davidson to put through the wrong surveillance paperwork, hiding his culpability behind a smokescreen of clumsiness. She thought she was manipulating him, but the reverse was true. Remember all those furtive looks from Buckells through the glass into Davidson’s office? He was watching her, rather than the other way around.

He pushed for the arrest of Terry Boyle (Tommy Jessop) because it fitted the “lone stalker” theory and led the investigation away from OCG involvement, justifying this as a hunger for results to impress his superiors. Buckells also pulled strings to disclose the identity of the CHIS, rent boy Alastair Oldroyd, who could confirm whether Terry was the mystery man bragging about Vella’s murder. Oldroyd was soon found dead. Buckells had blood on his faux-bumbling hands.

Series 6, episode 2: Golfing giveaway

Ever since Tommy Hunter was apprehended at Edge Park Golf Club, the sport has been synonymous with organised crime in Line Of Duty’s fictional universe. After all, Cottan got his “Caddy” nickname because he was groomed while carrying Hunter’s clubs.

It was an ominous sign early in series six when viewers spotted a golf bag stashed in the corner of Buckells’ office - not to mention framed photos of himself out on the fairways and greens. Golf clubs were later spotted in the boot of his car, alongside the missing Operation Lighthouse case files. Fore! Bent copper incoming!

Series 6, episode 3: Jobs for the boys

Buckells was swift to put forward probationary PC Ryan Pilkington for a commendation after the reservoir car crash, realising that such recognition would help fellow bent copper Ryan to climb through the ranks.

When Fleming credited Davidson for bringing Pilkington onto the team, she replied: “Not me, that was Buckells’ idea. Family friend or something. Probably got a nudge down at the Masonic lodge.” Those Freemasonry connections again, along with a reminder that he knew full well who Ryan was.

Series 6, episode 3: Caught but only temporarily

The third episode also saw Buckells arrested for his actions surrounding Operation Lighthouse – including those missing files and his links with Deborah Devereaux, a “witness” who owed him a favour after he got her off an assault charge years previously. She implicated Terry Boyle in what was clearly a false statement.

Few fans really believed that Buckells was in league with organised crime, instead buying into the idea that he’d been set up by Davidson. “Buckells couldn't run a bath, let alone an OCG,” as one viewer tweeted. Yet this was precisely what he wanted us to believe.

Davidson promptly went home, opened her laptop and typed into that secret online messaging service: “All under control now.” The mysterious “Unknown User” didn’t reply - but that’s because he was in AC-12 custody at the time.

• For the latest news and expert tips on getting the best deals this year, take a look at our Black Friday 2021 and Cyber Monday 2021 guides.

Series 6, episode 4: Wolf in sheep’s clothing

In the first of his two AC-12 interviews this series, Buckells was confronted with evidence of his involvement in the deaths of hitman Carl Banks, informant Alastair Oldroyd and drowned PC Lisa Patel - plus the failure of Operation Lighthouse, upon which he was the longest serving officer.

Once again, it looked to be ineptitude rather than incompetence (“I don’t know why I don’t know”). This illusion enabled him to hide in plain sight. Arnott didn’t believe Buckells could “organise a piss-up in a brewery” but Fleming foreshadowed the truth: “Yeah but that’s his cover.”

Sent to HMP Blackthorn, Buckwells distracted bent lawyer Jimmy Lakewell (Patrick Baladi) before OCG thug Lee Banks (Alastair Natkiel) garrotted him. We assumed this was simply a warning to Buckells but he was more complicit than he first appeared. The fact that he was visibly shaken was because he normally insulates himself from OCG violence, always several steps removed from the actions he helps orchestrate.

Despite Buckells’ weak defence against AC-12’s accusations, DCS Patricia Carmichael (Anna Maxwell Martin) deemed the case wasn’t watertight and dropped the charges against him. That hapless act had proved effective once again.

When the “Unknown User” fired up his messaging service again, he railed against AC-12 and ordered Davidson to “get rid of” Fleming. A move which wasn’t just expedient but the culmination of Buckells’ long-held hostility towards AC-12 and Kate in particular, who’d been a thorn in his side since series one. This time, it was personal.

Series 6, episode 7: Keyser Soze moment

Even during his climactic interview, Buckells kept up the act. He hid behind baffled looks, exasperated eye-rolls and tight-lipped “No comment”s. The mask only slipped when Hastings baited him with talk of “corruption hidden by incompetence” and being a “blundering fool”. Suddenly puffing up with arrogance, Buckells sneered: “Yeah right. I’m a blundering fool? I’m only the one who’s made total mugs out of you lot.”

Beneath the surface image of “crap suits and dad cars”, Buckells was leading a double life. He had a £3m property portfolio and bank accounts registered in the Cayman Islands.

AC-12 had tried to embarrass him about exchanging sexts with witnesses and suspects, but Buckells was unrepentant. “The big house, the fast cars, the bits on the side - is that what turned your head?”demanded Hastings. “Over the years, we’ve investigated all manner of motives but the basest, most mundane of all is plain, simple greed.”

• For the latest news and expert tips on getting the best deals this year, take a look at our Black Friday 2021 and Cyber Monday 2021 guides.

Buckells wasn’t a criminal mastermind. He was merely a middle man who accidentally rose through the ranks, did whatever he was asked to if the price was right, and ended up as the last bent copper standing. An unspectacular but all too plausible portrayal of the insidious nature of institutionalised corruption.

We ended with him in line for immunity and giving a self-satisfied smirk. If only Buckells could learn to spell “definately” correctly, he might still be at large. As a Scooby Doo villain might say: I would have gotten away with it too, if it wasn’t for those pesky typos.

Line of Duty season 6 is available on BBC iPlayer now, and we have all the latest news on Line of Duty season 7. Check out the rest of our Drama coverage, or take a look at our TV guide to find out what else is on.