Surely it can't be possible.
Superintendent Ted Hastings has been fighting anti-corruption for six series and always conducts himself "to the letter of the law".
Or so we thought, as there is an overwhelming amount of evidence mounting up against the much-loved head of AC-12.
The anti-corruption unit have been hunting for the mysterious 'fourth man' for years, but the top dog of the criminal network within the police force might actually be their leader.
Armchair detectives have also been trying to work out who H is, but few have pointed the finger at the gaffer himself.
From mysterious handshakes to spelling mistakes, there have been some deeply concerning incidents which could prove that Ted is a bent copper.
From his desperation for money to his suspicious underground connections, here is a look at the clues pointing to Ted as being H.
His surname
Perhaps the simplest and most logical reason for Ted being H is his surname.
"The name’s Hastings…like the battle," he famously said when introduced in the first series.
Obviously Ted's surname actually begins with the letter 'H', which has already been used against him.
In his dying declaration, Dot blinked to indicate the big baddy's name starts with a H and he gestured the same with his hand in morse code.
There have already been two senior officers with surnames beginning with H who were secretly affiliated with organised crime.
Assistant Chief Constable Derek Hilton and Detective Chief Inspector Lester Hargreaves were working for the OCG - and our both now dead and unable to answer for their crimes.
Could it simply be that Ted is guilty because his surname begins with H?
Secret handshakes
Ted was a good friend with former Chief Superintendent Patrick Fairbank before he was sent down.
The pair were both in the Freemasons and Steve caught his boss engaging in a Masonic handshake with Fairbank at his house before they interviewed the corrupt cop.
Although it's odd that Ted was allowed to join a Masonic organisation as Catholics are usually prohibited.
When Kate went undercover to investigate one of her own team members she got permission from AC-3 boss SI Madeleine Summers because as a female she definitely couldn’t be a Mason.
While in series 4, DCI Roz Huntley used Ted’s Masonic connections against him while she was under interrogation and claimed he was guilty of sexism.
There are clearly fears that there are links between corrupt police officers and Freemasonry, which have been investigated by AC-3.
Already part of one shady organisation, it would make sense if he was also part of another.
Spelling
This is definitely, or should that be 'definately', a solid piece of evidence against Ted.
In series 5, we saw that H was not particularly good with his spelling as he sent the message: "Eastfield Depot is definately high risk."
When Ted was supposedly posing as H as part of his unauthorised undercover op he wrote: "I can definately pull the right strings."
Under questioning from Patricia Carmichael, Ted awkwardly claimed he had studied the spelling habits of the corrupt officer and copied them.
But we didn't see Ted actually doing this and it sounded like something he quickly made up on the spot.
It could just be a massive coincidence or a smart move from Hastings - but somethings doesn’t add up with the bizarre spelling.
Destroying laptop
We were led to believe Ted was up to no good for most of series 5.
Ted started sending shady messages on his laptop and it looked suspiciously like those H was sending to the OCG members.
While being interviewed by Carmichael, Ted claimed it was all part of his undercover mission but one thing didn't make too much sense.
Red went to extreme measures to get rid of his laptop, covering it in bubble wrap before taking it to an electronic disposal shop.
Humiliated Ted confessed that it was because his wife had just left and he was watching pornographic material.
However, destroying his laptop seems a very extreme move for someone watching porn that he insisted was "nothing illegal, nothing extreme".
Financial issues
Ted's financial issues provide a clear motive for joining the OCG.
He may be one of the sharpest officers around but he isn't too good with money and lost all his life savings in a bad investment deal.
Without telling his wife, Ted invested in a property development site in Ireland which promised considerable returns.
But it all went wrong as they went bankrupt and took all his money, leaving Ted in financial ruin.
His furious wife Roisin left him and they were forced to sell their house, leaving Ted living in a tiny hotel room with a broken toilet.
In series 2, DI Lindsay Denton used Hastings’ money woes against him while she was being interrogated, as did Roz Huntley in series 4.
It even clouded his judgement when he initially refused to investigate DCC Mike Dryden because he offered to keep his financial difficulties secret and hinted at a promotion with a higher salary.
Ted tried to win Roisin back with a cruise but he couldn’t afford it and in series 5 she revealed she had met someone else and wanted a divorce.
He may have turned to crime to get his life back having lost his home and his wife due to money problems.
John Corbett connection
In series 5, Ted led a crusade against John Corbett.
He was determined to have him arrested, despite Steve and Kate arguing that he should be allowed to carry on his undercover mission.
Ted then gave the order for Steve to shoot Corbett dead after discovering that he was responsible for torturing his wife.
Was the reason he wanted rid of Corbett that he was close to rumbling him?
John was so convinced Ted was H that he risked his own life and ultimately died for it.
We then discovered that Ted had a secret connection to Corbett's mother, who was a police informant who was tortured and killed when she was exposed.
Hastings was also given £100,000 bribe money from the corrupt Mark Moffatt for his property development flop, but he kept half the cash to give to Corbett’s widow.
Backing corrupt officers
Hastings has a history of siding with bent officers
It’s a pattern that can’t be ignored and has nearly led to them getting away with their crimes on multiple occasions.
As previously stated, Ted was very reluctant to bring DCC Dryden in for questioning due to their working relationship.
Ted believed Dryden would keep his financial woes secret and get him a promotion so he was very reluctant to make him a suspect.
It was only after intense pressure from Kate and Steve along with undeniable evidence that he was forced to take action - and while Dryden wasn’t a criminal he did pervert the course of justice after being blackmailed.
A very similar scenario happened with former Chief Superintendent Patrick Fairbank, who was a close friend of Ted.
Fairbank not only covered up the sexual abuse of young boys at Sands View Boys Home but also used his position to take part in the vile acts himself.
When Steve and Kate went to question Fairbank at his home, Ted rocked up unexpectedly and made them them back off.
Let’s also not forget that it was Ted who recruited bent copper DI Matthew ‘Dot’ Cotton onto AC-12.
The Caddy was seconded from AC-9 to help investigate DI Denton - with Ted providing him secret information that he wouldn’t give to Kate or Steve.
He also took Dot’s side during his clash with Steve and nearly sent the innocent officer down for being The Caddy because he believed Dot’s lies.
There’s been too many instances of Ted defending bent coppers for it to be a coincidence.
Red Lion pub
Ted's choice of pub may hide a crucial clue.
In series 5 we saw Ted telling his team he was putting money behind the bar of the Red Lion pub to celebrate the unmasking of Assistant Chief Constable Derek Hilton as H.
Hasting told the team: "To celebrate, I am going to put a few bob behind the bar in the Red Lion tonight so you can all have a drink on the gaffer and that is something that does not happen every day. Correct? So carry on."
But the Red Lion has some criminal connections.
A confidential informant revealed he'd heard a man boasting about killing journalist Gail while in the boozer, which turned out to be Carl Banks.
It led to the arrest of Terry Boyle, who was subsequently cleared, while both Banks and the informant were later found dead.
It cropped up once again when DS Chris Lomax was overheard arranging to meet someone in the Red Lion, prompting suspicions he could have links to organised crime.
Could the Red Lion be the OCG's local?
Lee Banks visit
Ted was seemingly responsible for the death of John Corbett in series 5 because of his mysterious prison visit.
He paid a visit to see gang member Lee Banks at Blackthorn Prison but we didn’t find out what the pair discussed.
“Sit down, fella. This b*****d’s got a thing or two to say to you. Trust me. You’ll be glad you did,” he said.
Lisa McQueen would later reveal that it was Lee who told her there was a rat in the OCG.
It’s way too much of a coincidence that on the very same day, Corbett’s cover was blown and he was brutally murdered.
Who else would have managed to tell Lee about the mole while he was locked behind bars.
When DCS Carmichael was interviewing Ted she suggested he used the visit to blow Corbett’s cover.
It seems the most likely reason that Banks readied their was a leak in the OCG and passed the information on to his associates, who then disposed of Corbett.
Ted may have wanted to expose Corbett as an undercover cop so he would have to leave and co-operate with AC-12.
Or he might be part of the OCG and wanted to make sure the rat was eliminated.
Killing balaclava man
Ted seemingly became the hero at the end of series 4 - but it may not have been the incredible moment we first thought.
The AC-12 boss shot dead balaclava man while he was holding a security guard hostage during a dramatic stand-off.
Viewers cheered when Hastings managed to save the hostage by shooting the balaclava man with chilling precision.
Rather than shooting to subdue him, Ted fired one bullet straight into his head to make sure that he definitely died.
But there was no reason for Ted to take such a risky shot, which potentially could have killed one of his men, as they were surrounded by skilled Armed Firearms Officers.
This point was raised by John Corbett in the following series, who was convinced Ted was a corrupt cop.
Why was Ted so determined to make sure the balaclava man was killed?
Reckless behaviour
Ted famously claims he carries out his job "to the letter of the law", but he has gone against his own mantra many times.
His unauthorised mission to go undercover in the OCG nightclub was a risk to his life and career.
But why was he so determined to go alone without the proper measures being taken?
Straight-laced Ted has been a stickler for rules in the past and stuck to the normal procedures so this erratic behaviour is strange.
Perhaps the reason Ted would not authorise the undercover role was that he was hiding something.
The Ted that played by the rules is gone, so what else is he capable of?
Suspicious claims Ted isn't H
Line of Duty star Adrian Dunbar has been telling everyone that his character is definitely not H.
The actor claims show creator Jed Mercurio told him that Ted is not a corrupt officer.
"It was a relief for me, as I spent all this time playing this character and I always thought Ted had a sense of duty and a moral core," explained Dunbar last month.
"And to have found out I was this arch villain . . . I would have been in real difficulty accepting that.
"Jed is aware of our audience and they know Ted has a sense of moral fortitude. I am glad he came out of it with flying colours."
It seems strange that Line of Duty bosses who reveal such a major secret after keeping us guessing over Ted's loyalties for six series.
Could they be telling the truth, or could it just be another 'Ted Herring'?
*Line of Duty airs Sundays on BBC One at 9pm
