Line Of Duty fans convinced of shock secret link between Steph Corbett and Marcus Thurwell

Line Of Duty series six is set to reach its showstopping finale on Sunday, with AC-12 desperate to solve the mystery of the elusive fourth man, ‘H’.

And fans of the hit BBC crime show have stumbled across yet another shock theory that links John Corbett’s widow Steph to dodgy Marcus Thurwell – who was presumably found dead in the last episode.

Amid speculation that Thurwell (played by James Nesbitt) is alive and well, Line Of Duty have seemingly found a connection between the characters, with some believing the bent cop in hiding in Steph’s (Amy De Bhrún) Attic. 

Steph has made a number of appearances throughout the series and has seemingly been on edge and rather ill at ease each time. 

She also has a close link to AC-12, having allegedly received £50k from Ted Hastings (Adrian Dunbar) and of course slept with Steve Arnott (Martin Compston) amid his frequent visits.  

And avid viewers think that Marcus may have faked his own death and has been laying low with Steph the whole time, with many predicting Steph will play a big role in the finale. 

Taking to Twitter, one viewer shared: ‘I predict that Marcus Thurwell is living with Steph Corbett. The bodies in Spain were from the freezer.’

While another remarked: ‘I’m going to throw this out there ….I think Tommy Hunter is alive and has orchestrated Jo Davidson via the Laptop in Spain and Marcus Thurwell is staying with Steph Corbett and the money in the attic is his.’

Commenting on Steph’s suspicious behaviour, a third tweeted: ‘Just a thought, when Steve phones Steph why does she go outside to take the call? who does she not want hearing that.’

With another agreeing: ‘No, I wondered the same – definitely some Steph side eye and creeping around. Taking it to the extreme: John Corbett was from Northern Ireland, so is he linked to Thurwell in some way? Has Thurwell come back to the UK…? (Brexit Spanish-evictee style…).’ 

While thinking Steph’s role in the show is far from over, one viewer put: ‘I wonder if Steph Corbett will make an appearance in the final episode.’

As another shared: ‘cannot help thinking Steph is more involved’, with an additional watcher in agreement, writing: ‘Yes, Steph has been brought in so much, she’s got to have some part in it all.’

It comes as many viewers refused to believe that Marcuss Thurwell was found dead in his Spanish villa as AC-12 watched via video link, with several guessing he disguised as one of the Spanish officers conducting the raid. 

Towards the end of the nail-biting penultimate episode, Guardia Civil police officers stormed Marcus Thurwell’s Spanish home, while the AC-12 team watched via video link.

When the law enforcement officers entered the home, they were met by two bodies, and a Spanish captain turned to the camera and identified one as ‘Senor Thurwell’. 

While many viewers expressed surprise an actor of Nesbitt’s calibre was denied even a scene, some were left convinced Thurwell was in fact the Spanish AFO leading the raid on his home.

One tweeted: ‘Is it just me or was one of those Spanish “police officers” Thurwell? I’m sure it was him.’

Another wrote: ‘Exactly what I was thinking? Nice job if James Nesbitt only got paid for a few photos so I suspect that Marcus Thurwell is 100% alive.’

And one commented: ‘Is this Marcus Thurwell or have they just found the Spanish Jimmy Nesbitt to play the part?’ – sharing a series of screenshots to illustrate the likeness. 

AC-12 were looking into the retired former detective chief inspector after SI Steve Arnott (Martin Compston) learned that Gail Vella – the journalist who was murdered – had been looking into the death of Lawrence Christopher while in police custody – a case Thurwell was in charge of. 

Thurwell also has links to Darren Hunter, the son of former organised crime group boss Tommy Hunter.

The OCG also murdered Oliver Stephens-Lloyd before he had an opportunity to give evidence about sexual abuse at Sands View Boys’ Home, with Superintendent Ted Hastings convinced Thurwell is connected to the killing and the abuse cover-up. 

When Thurwell was found ‘dead’, Hastings was visibly exasperated – with time running out for him to solve the mystery before his impending retirement. 

Meanwhile, Martin Compston teased that fans will get some ‘big answers’ during the finale, as he admitted he believes it could be the ‘perfect ending’ to the police drama.

The actor, who plays DI Steve Arnott in the show, spoke to the Shrine Of Duty podcast ahead of the last episode this weekend.

Martin, 36, confessed that while he thinks Sunday’s episode could be the best way to wrap up the ‘story arch’ – he also refused to rule out another series.

When quizzed on whether viewers will learn who the illusive ‘H’ is, Martin said: ‘I wouldn’t quite go the Jo Davidson no comment route – but what I will tell you is I think there’s a lot of pay offs coming this Sunday.

‘There’s a lot of big answers and it’s deserved, people have stuck with us for a long time, so there comes a point where the story arch comes to an end.’

Martin also touched on whether series seven is likely, after show bosses previously claimed they believed the current season would be the last.

He said: ‘We don’t know [if there will be another] – that’s nothing new. Jed always takes time after a series, like a couple of months. 

‘There’s a lot of stuff above my pay grade like analytics and audience scores. He takes the emotion out of it and looks at all that.’

Admitting it could be the ‘perfect ending’, he said: ‘It’s different this year, because we have to look it in terms of, do people want us back? 10 years in you start to think of legacy, and if it goes down that well it might be the perfect ending.’

‘But then we might go another couple of months and… what I will say is we won’t do one just for the sake of doing it. Jed will only do it if there’s a story to be told.’

The chat comes days after a new trailer for Line Of Duty’s finale was released, only serving to heighten speculation around the identity of ‘H’. 

Viewers can be certain of an action-packed finale episode complete with a police standoff, the return of balaclava men and the discovery of a written note with THAT ‘definately’ misspelling. 

The trailer starts off with Superintendent Ted Hastings (Adrian Dunbar), who is facing imminent retirement, state: ‘All of these suspicious deaths were orchestrated by one officer in particular, H. The fourth man.’

Hastings’ powerful words went alongside flashbacks of the deaths of solicitor Jimmy Lakewell, police officer Lisa Patel, journalist Gail Vella and former Detective Inspector Marcus Thurwell- whom fans believe is still alive. 

The trailer then shows acting Superintendent Jo Davidson (Kelly MacDonald) leaving the high-security prison in handcuffs, only to end up alone in a van with a corrupt prison officer who previously injured Lindsay Denton in series three. 

A handwritten note is also teased in the trailer, with the word definite misspelt to mirror what viewers have seen previously.

A huge clue of the identity of H began to emerge in series five, when the OCG communicated with ‘H’ through a computer.

Eagle-eyed fans were quick to notice H spelling definitely as ‘definately’, and this misspelling has been repeated in subsequent episodes.

Will this handwritten report be the breakthrough AC-12 need to close in on ‘the fourth man’? 

It certainly seems Hastings and his team are on to something as police cars sped down the road, with armed officers closing in on a residential area during the trailer. 

The Superintendent briefs DI Kate Fleming, DI Steve Arnott and DC Chloe Bishop as they arrive at the scene.

Hastings says: ‘AFO’s will secure the suspect down’, while the words ‘Every investigation has led to this… H’.   

And it only gets more dramatic as balaclava men jump out of vehicles armed with guns themselves. 

Kate opens the police van, brandishes her gun and shouts: ‘armed police’ before the screen fades to black.   

The Line Of Duty series six finale airs on BBC One on Sunday at 9pm.