Line of Duty season 6's biggest red herrings, from Marcus Thurwell to Steph's kitchen tiles

To keep springing surprises after six series, he fills every episode with clues, callbacks and convolutions - some of which are false leads, deliberately designed to lead viewers (and AC-12) in the wrong direction.

With pause buttons being deployed, social media full of screengrabs and armchair detectives on the case - we see you, Jenny from Gogglebox with your special notebook - Mercurio stays one step ahead by distracting fans with all manner of McGuffins.

Here are 10 bluffs, feints and dummies that the ever-mercurial Mr Mercurio threw us during the sixth series. “Jed herrings”, if you will. How many did you fall for?

1. Chief Constable Philip Osborne

The widely predicted “big bad” turned out to be a glaring great decoy. All series, suspicion mounted that the corrupt conspiracy would go right to the top of Central Police. Would Chief Constable Philip Osborne (Owen Teale) be unmasked as “The Fourth Man” running the shady show?

Sorry. Just when you thought Ser Alliser Thorne in Game Of Thrones was Teale’s most hateful role… er, it still is.

Yes, Osborne orchestrated a counter-terror cover-up in series one. Yes, he was among the dodgy detectives who bungled the Lawrence Christopher case. Yes, he’s on a mission to strip anti-corruption of its powers. And yes, in AC-12’s interview of DCI Jo Davidson (Kelly Macdonald), the Chief Constable’s loyal lapdog DCS Patricia Carmichael (Anna Maxwell Martin) repeatedly steered conversation away from any mention of her boss and swiftly changed the subject whenever institutional corruption came up.

However, patronising Pat seemed to be covering the boss’ backside for political and publicity reasons. Osborne and Carmichael - like the “mahogany office” duo of PCC Rohan Sindwhani (Ace Bhatti) and DCC Andrea Wise (Elizabeth Rider), another pair of huge Jed herrings - were more worried about reputational damage than rooting out wrongdoers. One rotten apple they could stomach but not the whole barrel, fella.

Osborne didn’t even appear properly on-screen. We only glimpsed him on news footage, making pompous speeches to the press from the steps of City Hall, while Hastings and Arnott scowled at the telly.

We still trust Osborne about as far as we can throw the AC-12 photocopier but he’s slipped the net for now. One to save for another series, perhaps (hint, hint).

2. The Spanish IP address

When the all-knowing Amanda Yao (Rosa Escoda) from Cybercrime traced the sinister online messaging service’s “Unknown User” to Spain, sofa sleuths gleefully seized upon this seemingly crucial detail. “Aha!” they cried. Retired DCI Marcus Thurwell (James Nesbitt) was last seen in Spain, muttering furtively into a mobile. He’s clearly giving the orders and pulling the strings from afar. He’s Señor H! He’s The Fourth Hombre!

Yet not only was Thurwell already strangled dead in his bed but cult heroine Amanda soon worked out that the messages originated in the UK anyway. They were just rerouted via Spain to mask Unknown User’s true location.

Thurwell was basically just a bloke with a modem who owed the OCG a few favours. El Swizz. No wonder Ted Hastings thumped a desk in dismay.

3. DCI Marcus Thurwell

Hell, it wasn’t just Thurwell’s IP address which was a Jed herring. His entire character was. The shock arrival of big-name actor Nesbitt in episode five caused a collective intake of breath. Was that nice twinkly chap from Cold Feet about to arrive as the arch villain?

Mother of God, no. Thurwell was as bent as a burner phone, sure, but largely just a fixer for the more monstrous CSU Patrick Fairbank (George Costigan). When the going got tough, Thurwell took early retirement and fled to the Costa Del Crime, like a less leathery Ray Winstone from Sexy Beast.

Even when “Marcooth” was found strangled in his villa bed last week, viewers were convinced Thurwell had faked his own death and would miraculously rise from the grave for the finale. Some even surmised from his eyebrows alone that the Guardia Civil captain leading the armed raid was Thurwell himself in disguise.

No such luck. Nesbitt’s stint instead goes down as one of the shortest and strangest in Line Of Duty history, appearing in only three photos and as a fly-covered corpse down a helmet-cam’s infrared feed. It was an impudent piece of stunt casting which fooled millions and enabled the real “H” to hide in plain sight. Why I oughta. Jed 'n' Jim, you wags.

4. Pat's pass-agg pen-tapping

Sighing, fake-smiling DCS Carmichael might be a brilliantly awful creation but some conspiracy theorists became a tad too obsessed with unmasking her as “H”. The Fourth Man actually being a woman would have been a neatly progressive twist, sure, but it was also a bit of a reach.

One straw clutched by fans was her impatient pen-tapping during Davidson's interview. Eagle-eyed viewers noticed that Carmichael tapped it on the table four times. And, of course, four dots signify the letter “H” in Morse code - which DI Steve Arnott (Martin Compston) discovered last series when he re-examined the dying declaration of DI Matthew “Dot” Cottan (Craig Parkinson), aka The Caddy.

"Carmichael is H!” tweeted one triumphant viewer. “She tapped her pen four times – H in morse code – and took a sip of water. The guilty ones always drink water in the interview room.”

The next day on ITV’s This Morning, Maxwell Martin pooh-poohed the notion. "I think I was just bored,” she laughed. “Those scenes are very long. I was like, ‘What am I saying next?’” Yes, but she *would* say that, right? Um, wrong.

5. Chloë’s name

The scarily efficient DC Chloë Bishop (Shalom Brune-Franklin) proved a superb addition to the AC-12 squad this series. Ice-cool in the action scenes, confidently convincing with the lingo, righteously impassioned about institutionalised racism. But wait up, what about that whole name thing?

There was widespread speculation on social media that she could secretly be the daughter of series one antagonist DCI Tony Gates (Lennie James). He had two young daughters, Natalie and Chloë, who’d be around Bishop’s age now. Was she on a revenge mission against the gangsters who caused her father’s death? Was she covertly embedded in the force like PC Ryan and leaking intel to the OCG?

Nothing sinister whatsoever, we’re afraid. Just doing her job terrifyingly well. “Outstanding work, Chloë,” as SuperTed said.

6. Davidson’s second dad

Who's the daddy? Coming into the season finale, one of the big mysteries was the identity of the man Jo Davidson believed to be her father – whether she was talking about an adopted dad, or a rapist who impregnated her mother. “Uncle Tommy” might have secretly been her biological dad, but until her AC-12 interview she was totally convinced that another man, a bentcopper™ and criminal associate of Tommy’s, was her father. Who? And was he still controlling and coercing her?

Nope. It was convicted paedophile Fairbank, but the retired vice cop, suffering from dementia, couldn’t even remember – or perhaps Tommy Hunter had never even told him about the big lie to young Jo. Fairbank was certainly incapable of running police corruption from inside Queen’s Chase Open Prison. Another dead end. Hmph.

7. Dodgy DI Lomax

Right from the start, DS Chris Lomax (Perry Fitzpatrick) looked vaguely shifty. It was him who took that curtain-raising late-night call from the CHIS handler. The fact that with his lanky frame, deadpan tones and moody expression, Lomax rather resembled The Caddy didn’t help.

He was hostile to AC-12 throughout their inquiry (“Don’t be a tit, Sarge,” as Fleming ended up telling him). When M.I.T were told to hand over their phones to prevent leaks about the firearms workshop raid, Lomax was even more huffy about it than bent colleague PC Ryan Pilkington (Gregory Piper).

Viewers pounced on potential clues that Lomax drank in the Red Lion pub, as did OCG gunman Carl Banks, and bore a resemblance to one of the mugshots of Lawrence Christopher’s racist attackers. Even in the series finale, Lomax’s signature was on that faked production order to transport Davidson out of prison, leaving her at the mercy of Balaclava Men in black Range Rovers.

It turned out that Lomax wasn’t bent, just a bit mardy. And possibly had some cringey selfies on his phone. Don’t be a tit, Sarge.

8. Carmichael’s incriminating anagram

Along with that pesky pen-tapping, Carmichael spawned another feverish conspiracy theory. In episode four, jailed lawyer Jimmy Lakewell (Patrick Baladi) advised Arnott to “Look beyond the race claim”. What do you get if you take the letters in “race claim” away from “Carmichael”? That’s right - the single letter “H”.

"One of my favourite things is reading all the fan theories,” said Martin Compston this week. “Some are absolutely wild. I saw that anagram one. You just wonder who's got time to sit there and come up with these things."

Sadly, Line Of Duty didn’t turn out to be a cryptic crossword in TV form. Besides, there’s no way that smug, swotty Carmichael wouldn’t know how to spell “definately”.

9. Arnott’s career crisis

When we rejoined AC-12 seven hectic weeks ago, waistcoat-clad crusader Arnott was clearly unhappy. He was missing his “mate” Fleming. He had no juicy cases to sink his terrier-like teeth into. He was popping pills, chugging booze and hiding his unhappiness behind a red flag of a beard.

Steve was soon tapping up his ex-squeeze DI Nicola “Jolly” Rogerson (Christina Chong) for a transfer to her Serious & Organised Crime Unit. Except it never happened. Hastings repaid Arnott for his loyalty by promoting him from DS to DI. Steve told Nic to hold off for a while. It was never mentioned again.

Although he might re-apply now that creepy Carmichael is his new boss. “The usual” at Caffè Nero, Steve?

• 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.

10. Steph Corbett’s kitchen tiles

Quick, freeze frame that shot of her kitchen wall! See? Told you! Yes, there was much excitement among armchair detectives when they spotted a telling decor detail at the home of Steph Corbett (Amy De Bhrún), widow of series five’s undercover cop DS John Corbett (Stephen Graham).

Just behind her mug tree was a ceramic wall tile with an “H”-shaped mosaic pattern. Was this a subtle hint that the Arnott-spooning, white wine-sipping Scouse hairdresser was our criminal mastermind? No, it wasn’t. It was literally just a tile. Chill out, everyone.

Want more analysis of the finale? Read our Line of Duty ending explainer, or see all of the Line of Duty unanswered questions left up in the air.

Line of Duty is available to watch now on BBC iPlayer – check out our Drama hub for all the latest news, or our TV Guide to find something to watch tonight.By: Michael Hogan

Quick, look over there! Fooled you. Yes, like a skilled magician or a fibbing politician, Line Of Duty mastermind Jed Mercurio is a master of misdirection.

To keep springing surprises after six series, he fills every episode with clues, callbacks and convolutions - some of which are false leads, deliberately designed to lead viewers (and AC-12) in the wrong direction.

With pause buttons being deployed, social media full of screengrabs and armchair detectives on the case - we see you, Jenny from Gogglebox with your special notebook - Mercurio stays one step ahead by distracting fans with all manner of McGuffins.

Here are 10 bluffs, feints and dummies that the ever-mercurial Mr Mercurio threw us during the sixth series. “Jed herrings”, if you will. How many did you fall for?

1. Chief Constable Philip Osborne

The widely predicted “big bad” turned out to be a glaring great decoy. All series, suspicion mounted that the corrupt conspiracy would go right to the top of Central Police. Would Chief Constable Philip Osborne (Owen Teale) be unmasked as “The Fourth Man” running the shady show?

Sorry. Just when you thought Ser Alliser Thorne in Game Of Thrones was Teale’s most hateful role… er, it still is.

Yes, Osborne orchestrated a counter-terror cover-up in series one. Yes, he was among the dodgy detectives who bungled the Lawrence Christopher case. Yes, he’s on a mission to strip anti-corruption of its powers. And yes, in AC-12’s interview of DCI Jo Davidson (Kelly Macdonald), the Chief Constable’s loyal lapdog DCS Patricia Carmichael (Anna Maxwell Martin) repeatedly steered conversation away from any mention of her boss and swiftly changed the subject whenever institutional corruption came up.

However, patronising Pat seemed to be covering the boss’ backside for political and publicity reasons. Osborne and Carmichael - like the “mahogany office” duo of PCC Rohan Sindwhani (Ace Bhatti) and DCC Andrea Wise (Elizabeth Rider), another pair of huge Jed herrings - were more worried about reputational damage than rooting out wrongdoers. One rotten apple they could stomach but not the whole barrel, fella.

Osborne didn’t even appear properly on-screen. We only glimpsed him on news footage, making pompous speeches to the press from the steps of City Hall, while Hastings and Arnott scowled at the telly.

We still trust Osborne about as far as we can throw the AC-12 photocopier but he’s slipped the net for now. One to save for another series, perhaps (hint, hint).

2. The Spanish IP address

When the all-knowing Amanda Yao (Rosa Escoda) from Cybercrime traced the sinister online messaging service’s “Unknown User” to Spain, sofa sleuths gleefully seized upon this seemingly crucial detail. “Aha!” they cried. Retired DCI Marcus Thurwell (James Nesbitt) was last seen in Spain, muttering furtively into a mobile. He’s clearly giving the orders and pulling the strings from afar. He’s Señor H! He’s The Fourth Hombre!

Yet not only was Thurwell already strangled dead in his bed but cult heroine Amanda soon worked out that the messages originated in the UK anyway. They were just rerouted via Spain to mask Unknown User’s true location.

Thurwell was basically just a bloke with a modem who owed the OCG a few favours. El Swizz. No wonder Ted Hastings thumped a desk in dismay.

3. DCI Marcus Thurwell

Hell, it wasn’t just Thurwell’s IP address which was a Jed herring. His entire character was. The shock arrival of big-name actor Nesbitt in episode five caused a collective intake of breath. Was that nice twinkly chap from Cold Feet about to arrive as the arch villain?

Mother of God, no. Thurwell was as bent as a burner phone, sure, but largely just a fixer for the more monstrous CSU Patrick Fairbank (George Costigan). When the going got tough, Thurwell took early retirement and fled to the Costa Del Crime, like a less leathery Ray Winstone from Sexy Beast.

Even when “Marcooth” was found strangled in his villa bed last week, viewers were convinced Thurwell had faked his own death and would miraculously rise from the grave for the finale. Some even surmised from his eyebrows alone that the Guardia Civil captain leading the armed raid was Thurwell himself in disguise.

No such luck. Nesbitt’s stint instead goes down as one of the shortest and strangest in Line Of Duty history, appearing in only three photos and as a fly-covered corpse down a helmet-cam’s infrared feed. It was an impudent piece of stunt casting which fooled millions and enabled the real “H” to hide in plain sight. Why I oughta. Jed 'n' Jim, you wags.

4. Pat's pass-agg pen-tapping

Sighing, fake-smiling DCS Carmichael might be a brilliantly awful creation but some conspiracy theorists became a tad too obsessed with unmasking her as “H”. The Fourth Man actually being a woman would have been a neatly progressive twist, sure, but it was also a bit of a reach.

One straw clutched by fans was her impatient pen-tapping during Davidson's interview. Eagle-eyed viewers noticed that Carmichael tapped it on the table four times. And, of course, four dots signify the letter “H” in Morse code - which DI Steve Arnott (Martin Compston) discovered last series when he re-examined the dying declaration of DI Matthew “Dot” Cottan (Craig Parkinson), aka The Caddy.

"Carmichael is H!” tweeted one triumphant viewer. “She tapped her pen four times – H in morse code – and took a sip of water. The guilty ones always drink water in the interview room.”

The next day on ITV’s This Morning, Maxwell Martin pooh-poohed the notion. "I think I was just bored,” she laughed. “Those scenes are very long. I was like, ‘What am I saying next?’” Yes, but she *would* say that, right? Um, wrong.

5. Chloë’s name

The scarily efficient DC Chloë Bishop (Shalom Brune-Franklin) proved a superb addition to the AC-12 squad this series. Ice-cool in the action scenes, confidently convincing with the lingo, righteously impassioned about institutionalised racism. But wait up, what about that whole name thing?

There was widespread speculation on social media that she could secretly be the daughter of series one antagonist DCI Tony Gates (Lennie James). He had two young daughters, Natalie and Chloë, who’d be around Bishop’s age now. Was she on a revenge mission against the gangsters who caused her father’s death? Was she covertly embedded in the force like PC Ryan and leaking intel to the OCG?

Nothing sinister whatsoever, we’re afraid. Just doing her job terrifyingly well. “Outstanding work, Chloë,” as SuperTed said.

6. Davidson’s second dad

Who's the daddy? Coming into the season finale, one of the big mysteries was the identity of the man Jo Davidson believed to be her father – whether she was talking about an adopted dad, or a rapist who impregnated her mother. “Uncle Tommy” might have secretly been her biological dad, but until her AC-12 interview she was totally convinced that another man, a bentcopper™ and criminal associate of Tommy’s, was her father. Who? And was he still controlling and coercing her?

Nope. It was convicted paedophile Fairbank, but the retired vice cop, suffering from dementia, couldn’t even remember – or perhaps Tommy Hunter had never even told him about the big lie to young Jo. Fairbank was certainly incapable of running police corruption from inside Queen’s Chase Open Prison. Another dead end. Hmph.

7. Dodgy DI Lomax

Right from the start, DS Chris Lomax (Perry Fitzpatrick) looked vaguely shifty. It was him who took that curtain-raising late-night call from the CHIS handler. The fact that with his lanky frame, deadpan tones and moody expression, Lomax rather resembled The Caddy didn’t help.

He was hostile to AC-12 throughout their inquiry (“Don’t be a tit, Sarge,” as Fleming ended up telling him). When M.I.T were told to hand over their phones to prevent leaks about the firearms workshop raid, Lomax was even more huffy about it than bent colleague PC Ryan Pilkington (Gregory Piper).

Viewers pounced on potential clues that Lomax drank in the Red Lion pub, as did OCG gunman Carl Banks, and bore a resemblance to one of the mugshots of Lawrence Christopher’s racist attackers. Even in the series finale, Lomax’s signature was on that faked production order to transport Davidson out of prison, leaving her at the mercy of Balaclava Men in black Range Rovers.

It turned out that Lomax wasn’t bent, just a bit mardy. And possibly had some cringey selfies on his phone. Don’t be a tit, Sarge.

8. Carmichael’s incriminating anagram

Along with that pesky pen-tapping, Carmichael spawned another feverish conspiracy theory. In episode four, jailed lawyer Jimmy Lakewell (Patrick Baladi) advised Arnott to “Look beyond the race claim”. What do you get if you take the letters in “race claim” away from “Carmichael”? That’s right - the single letter “H”.

"One of my favourite things is reading all the fan theories,” said Martin Compston this week. “Some are absolutely wild. I saw that anagram one. You just wonder who's got time to sit there and come up with these things."

Sadly, Line Of Duty didn’t turn out to be a cryptic crossword in TV form. Besides, there’s no way that smug, swotty Carmichael wouldn’t know how to spell “definately”.

9. Arnott’s career crisis

When we rejoined AC-12 seven hectic weeks ago, waistcoat-clad crusader Arnott was clearly unhappy. He was missing his “mate” Fleming. He had no juicy cases to sink his terrier-like teeth into. He was popping pills, chugging booze and hiding his unhappiness behind a red flag of a beard.

Steve was soon tapping up his ex-squeeze DI Nicola “Jolly” Rogerson (Christina Chong) for a transfer to her Serious & Organised Crime Unit. Except it never happened. Hastings repaid Arnott for his loyalty by promoting him from DS to DI. Steve told Nic to hold off for a while. It was never mentioned again.

Although he might re-apply now that creepy Carmichael is his new boss. “The usual” at Caffè Nero, Steve?

• 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.

10. Steph Corbett’s kitchen tiles

Quick, freeze frame that shot of her kitchen wall! See? Told you! Yes, there was much excitement among armchair detectives when they spotted a telling decor detail at the home of Steph Corbett (Amy De Bhrún), widow of series five’s undercover cop DS John Corbett (Stephen Graham).

Just behind her mug tree was a ceramic wall tile with an “H”-shaped mosaic pattern. Was this a subtle hint that the Arnott-spooning, white wine-sipping Scouse hairdresser was our criminal mastermind? No, it wasn’t. It was literally just a tile. Chill out, everyone.

Want more analysis of the finale? Read our Line of Duty ending explainer, or see all of the Line of Duty unanswered questions left up in the air.

Line of Duty is available to watch now on BBC iPlayer – check out our Drama hub for all the latest news, or our TV Guide to find something to watch tonight.