Ominous signs suggest Line of Duty is in its final season – but is this really the end?

As we hurtle towards the white-knuckle series finale with more questions than an AC-12 interview, many pundits are confidently predicting it will be the last episode ever. Well, like any S.I.O worth their rank, let’s examine the evidence for and against.

First, the ominous signs. Line of Duty season six so far has frequently felt like an extended endgame, as if writer Jed Mercurio is arranging his chess pieces for a final offensive.

Murdered journalist Gail Vella (Andi Osho) appears to have been assassinated because she was investigating the very same scandals - child sex abuse cover-ups, bungled counter-terror ops, links between bentcoppers™ and organised crime - that anti-corruption unit AC-12 have painstakingly probed. The plot is beginning to creak under the weight of its own internal mythology, as if preparing for one last push.

Signs of winding up are everywhere. AC-12 is being disbanded. Its morally righteous leader, Supt Ted Hastings (Adrian Dunbar), is being forced into early retirement. His senior investigator, DI Steve Arnott (Martin Compston), risks being fired for painkiller addiction. Meanwhile, there are signs that both he and “work wife” DI Kate Fleming (Vicky McClure) are suffering from PTSD due to all the violent deaths they’ve witnessed.

For six series, this dream team have been desperately trying to crack the corrupt conspiracy at the heart of Central Police force. They could be about to unravel the last thread and go out in a blaze of glory. And acronyms.

This breathlessly thrilling series has incorporated multiple callbacks to previous investigations - not just the more recent runs but harking all the way back to the debut series. Characters like Tommy Hunter (Brian McCardie), Philip Osborne (Owen Teale), Ian Buckells (Nigel Boyle), Terry Boyle (Tommy Jessop) and Ryan Pilkington (Gregory Piper) first popped up in 2012. Bringing them back for the final act would have a pleasing circularity.

Early buzz on Sunday night’s must-see finale suggests it will wrap up long-running storylines satisfyingly. “Every investigation has led to this”, as the trailer goes. This series being extended to an unprecedented seventh episode and the addition of a top-secret second guest star (James Nesbitt joining Kelly Macdonald) could also be clues that something conclusive is afoot.

Everything is converging with an air of finality. If proceedings climax by unmasking the corrupt kingpin known as “H”, aka The Fourth Man, it might well feel like a natural end.

Alternatively - and this is where our optimism kicks in - it could just mark the end of a chapter, rather than the sprawling saga as a whole. When I interviewed actor Martin Compston in March, he told me: “Series three was a favourite of ours because it was the culmination of a three-series story. This one feels similar. We’re coming to another climax and a lot of big questions get answered.”

If the first three series were one chapter (essentially The Caddy’s story), he said, then series four to six have been another (the mystery of “H”, aka The Fourth Man).

Framed like this, another series could simply mean it’s time for a whole new chapter to kick off. A new bent copper, a new shadowy criminal mastermind, perhaps even a new AC-12 team - or our existing dream trio (plus, if they’ve got any sense, DC Chloë Bishop and Cybercrime’s Amanda Yao) reunited elsewhere. There are ways to reboot, refresh and restart without taking down those evidence boards forever.

Worryingly for fans, another series is yet to be commissioned. “We’re in a situation where it’s not entirely clear that there will be a seventh series,” said Mercurio at launch time. “We would hope there could be. But we’re having to do our planning coming out of COVID, and a whole bunch of other things, around the idea that these things aren’t guaranteed at all now.”

More promisingly, he said on Jay Rayner’s Out To Lunch podcast in February: “In terms of immediate ambitions, I really want to carry on with Line Of Duty. I think that season six proves that there is much more ground for us still to cover.”

At the time of writing, the BBC confirm there is “no news” about a seventh series. But following blockbuster ratings this time - not to mention Line Of Duty becoming a meme machine and fully-fledged cultural phenomenon - the Corporation will surely be begging Mercurio for more. Not to encourage malfeasance in public office but execs could try leaving cash-stuffed Jiffy bags in his hotel room.

The ball is in Mercurio's court. It’s just a question of whether he wants to make more and feels inspired to construct another compelling narrative. As he said two months ago: “A lot of it depends on the key creatives - that’s me and the main actors - finding new stories to tell within that universe.”

The in-demand writer and showrunner might be keen to pursue other projects. Hollywood could come calling. He might fancy turning his hand to a different genre, like his briefcase-bombing 2018 hit Bodyguard.

His recently formed HTM Television company is ramping up its production slate. Already in the pipeline are a second series of Ulster noir Bloodlands, bomb disposal thriller Trigger Point (starring a certain Vicky McClure) and a Stephen Lawrence series for ITV. Mercurio will also script a new Netflix political thriller, an adaptation of Fletcher Knebel's 1965 novel Night Of Camp David, with Oscar-nominated Paul Greengrass directing.

Yet Mercurio always stresses that Line Of Duty is a team effort, a family affair, and its cast and crew would doubtless jump at the chance to go again. They’re keen to make at least one more series, if only because the current one was filmed in such an unusual way.

There was a seven-month shooting break. When work did resume, masks were worn, scenes were relocated outdoors and social distancing was practised. There were no team-bonding nights out nor wrap parties.

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Such COVID-safe measures all worked well, as you might expect with a former hospital doctor at the helm, and there were no serious health scares. But it was by no means business as usual in Belfast and the atmosphere on-set was markedly different.

Understandably, the performers and production team - many of whom have been with the show since the very beginning - would prefer to end on a “proper” series and enjoy the send-off they deserve after a decade of phenomenal success. Don’t be surprised if the next series is just footage of them eating curries, pranking the long-suffering Dunbar and doing daft TikTok dances.

As Dunbar has said: “We’ve got to do another series. We’ve got to get onto Jed and say ‘Look, we’ve got to do one that’s not like when we were in lockdown. We’ve got to do one where we’re back on the ground and out there in the city.’ Belfast is a great place to have fun, so we really want to get back to doing that again.”

Compston has echoed the gaffer’s sentiment, suggesting that even post-“H”, there’s still legs in Line Of Duty: “I think with Jed, there’s potential for it to go on. He could always start a new case. There’s always corruption out there, as he would say.”

So what does the future hold for hair-smoothing Hastings, action heroine Fleming and resident Romeo Arnott? Assuming they survive the series finale (gulp), will they ever step into that glass lift up to AC-12 HQ again? Will “mate” or “Mother of God” be repeatedly said during a seventh series?

In the absence of an official announcement from the BBC or Mr Mercurio himself, the case file remains open.

Until then, our CHIS has been graded on the credibility matrix and premature reports of Line Of Duty’s death have been greatly exaggerated. Interview not terminated. Just paused. But for the benefit of the DIR, we’d love more please.

Series six of Line of Duty concludes this Sunday night, 9pm on BBC One. To find out what else is on, or to decide on your viewing for tonight, check out our TV Guide.