The last few seasons of the hit BBC One police drama have focused on the hunt for “H”, the name given to a corrupt officer working within the upper echelons of the police.
While series five revealed that “H” was in fact not one person but several, the search remains ongoing for the last “H”, also referred to as “the fourth man”.
Over the course of Line of Duty’s sixth series, fans have spotted kitchen tiles, Easter eggs, misspellings and even anagrams that they believe could reveal H’s identity.
Here are some of the potential clues and suspects for H’s identity we’ve seen in season six…
On the wall was a painting depicting the silhouette of a person swinging a golf club.
Dedicated fans of the show will know that the hobby of golf has strong ties to the corrupt syndicate, H.
This was revealed via DI Matthew Cottan (Craig Parkinson), who was outed in series three as “The Caddy”.
The story went that Cottan had been working as golf caddy for gangster Tommy Hunter (Brian McCardie), who groomed him and convinced him to become a mole within the police force.
However, Buckells was arrested midway through the season, and seems to be little more than a patsy for the OCG (organised crime group).
Steph Corbett’s tiles
Arnott was seen once again visiting Steph Corbett (Amy De Bhrún), the widow of slain undercover officer John Corbett (Stephen Graham).
As the pair chatted in Corbett’s kitchen, some viewers were fixated not on the conversation, but on the tiled pattern on the wall behind Arnott.
The majority of the tiles were blank, but one of them carried a pattern that distinctly resembled the letter “H”.
It’s not clear exactly what the clue would mean, however, with Corbett not working for the police, and her late husband having been murdered by the OCG.
It’s possible that the Easter egg, if deliberate, hints that Steph could hold the key to identifying the “fourth man”, even if she herself is not a candidate.
In episode four, viewers saw the imprisoned OCG lawyer Jimmy Lakewell (Patrick Baladi) talk to Arnott, who was attempting to get him to turn informant.
Speaking about the death of journalist Gail Vella, Lakewell told Arnott he needed to “look beyond the race claim to find H”.
As many fans subsequently pointed out on social media, “race claim” is almost an anagram for “Carmichael”, minus one letter: H.
Coincidence or not, the next episode saw the return of the supercilious Detective Chief Superintendent Patricia Carmichael, played by Anna Maxwell Martin. Could she be H?
In an Instagram post, Martin misspelled the word “definitely” as “definately” - the same mistake that appears in Jo Davidson’s (Kelly Macdonald) communications with a mystery handler.
Episode six also saw Carmichael repeatedly trying to move AC-12 away from their investigation into the “fourth man” and institutional corruption, and she kept saying she preferred to focus on the smaller picture: whether Davidson is corrupt.
In the same interrogation, Carmichael tapped her pen four times, which is morse code for “H”. As soon as she did this, Davidson went from being quite candid straight back to “no comment”. Was it a warning?
Fans speculated that Superintendent Ted Hastings could be H after Arnott managed to trace the OCG money he found during an illegal search of Steph Corbett’s house back to his gaffer.
He flagged his findings to DI Kate Fleming (Vicky McClure), telling her that he suspected he knew the real reason why Hastings handed Corbett the money.
Viewers also saw Hastings argue against arresting crooked PC Ryan Pilkington (Gregory Piper), despite having caught him on camera appearing to tip off the OCG about a police raid.
As Arnott noted to Fleming shortly afterwards, he had taken the exact opposite position on bringing in Pilkington before.
The episode also saw Arnott speak to the imprisoned Lee Banks (Alastair Natkiel), who told him that Hastings had alerted him to the fact there was a rat within the OCG last season, which turned out to be John Corbett.
There’s also the matter of a spelling mistake in Jo Davidson’s communications with a mystery handler – the anonymous conspirator spelled “definitely” as “definately”, exactly how Hastings has done in the past.
Chief Constable of Central Police Osborne has been suspicious since the very first series, when he was the head of anti-terrorism and Arnott’s boss. When a mission went wrong, resulting in the death of an innocent member of the public, Osborne pressured his team to lie and cover it up - a level Arnott refused to sink to.
In season six, Osborne is using his power and influence to discredit the work of Hastings and AC-12. He has also been named as one of Marcus Thurwell’s (James Nesbitt’s) team and therefore one of the officers on the Lawrence Christopher case. Christopher was a young Black man who was killed in a racially-motivated attack that was not investigated properly by police - his case was being dug into by murdered journalist Gail Vella.
It was Osborne’s decision to merge and cut the anti-corruption units, and he was the one who sent Detective Chief Superintendent Patricia Carmichael (previously in charge of AC-3) to take charge of AC-12. In episode six, Carmichael ordered the removal of Osborne’s image from the corruption investigation board and every time his name comes up in relation to the scandal, she tries to move the conversation on.
Under Osborne’s direct orders, the surveillance on Davidson and Pilkington was pulled on the night they lured Fleming to a car park and tried to kill her.
According to a fan theory, the dodgy copper is none other than DS Chris Lomax (Perry Fitzpatrick), the officer who has been seen working closely with Fleming throughout the season.
Fans first speculated that Lomax could be bent after noticing a visual similarity between Lomax and a photo of one of the suspects in the historic Lawrence Christopher murder.
While that may seem like a stretch, it’s worth remembering that Lomax’s picture was included on AC-12’s investigation board. And what’s more, one moment in episode six provided the biggest hint yet that Lomax may have ties to the OCG (organised crime group).
Near the end of the episode, Lomax was seen at the OCG workshop, as a police forensic team combed for evidence.
At the start of the scene, he was heard telling a colleague that they could “be in the Red Lion by 8pm”.
As some viewers pointed out, the Red Lion is the pub in which Carl Banks bragged about murdering Gail Vella earlier this season, leading some to suspect it is a common OCG meeting ground.