Closure is an elusive concept. Life’s most challenging situations rarely provide it.

Take relationship break-ups. When you’ve been dumped have you ever been able to say: “Well fair play he/she might have ripped my heart out and stamped on it but at least he/she fully explained his/her actions with sensitivity, consideration and compassion – so much so I am able to move on happily feeling minimal psychological damage”? Of course not.

But if endings are inevitably messy in real life, on the small screen they can be so infuriating they leave viewers as traumatised by fictional drama as personal drama.

The frustration is all the more annoying because we know that, unlike life, we are not at the mercy of the random events of the universe – we’ve just been shafted by the script-writers. Your ex won’t give you the satisfying ending you want but a dramatist could, if he or she chose to.

But the fashion in long-running television shows is to avoid crowd-pleasing resolution at all costs. As 10 years and six seasons of Line of Duty reached its climax last Sunday the only thing H turned out to stand for was hysteria as the Twitterverse and Facebook world combusted with incredulity.

Adrian Dunbar as Superintendent Ted Hastings

When you’ve lived every last plot twist, character development and discarded enough red herrings to fill Ashton’s fish market, you ache for a decent denouement. But what did we get? Buckells. Yes, the bent copper controlling a complex web of organised crime networks whose identity had tortured AC12’s finest minds and obsessed 13 million viewers for 36 episodes turned out to be... gormless, workshy DCI Ian Buckells.

Evil criminal mastermind? More like Noddy Holder’s idiot lovechild. And he’d been hiding in plain sight all along. In hindsight, however, it was obvious. Buckells was always the character who wouldn’t have been able to spell “definitely”.

With the Fourth Man unveiled in such underwhelming circumstances, frustrated fans were left demanding a seventh season. Few could bear to contemplate that really was it.

The only person who deserved to feel more hard done by was Chloe, who mastered a script more detailed and acronym-laden than the manual for the Space Shuttle and cracked the entire case without even getting invited to the pub.

But it’s only telly isn’t it? Well yes and no. We viewers invest a lot of emotional energy in these compelling narratives. Not to mention hours and hours and hours of time. So it’s no wonder inconclusive conclusions leave us screaming at the screen.

The sense of exasperation that accompanied the final credits triggered memories of previous televisual anti-climaxes. Before his agent persuaded him to take the role of a passport photo in Line of Duty, James Nesbitt gave the performance of his career in The Missing in 2014.

The drama told the disturbing tale of the sudden disappearance of a six-year-old boy called Oliver while on holiday with his parents – played by Nesbitt and Frances O’Connor – in France. It had a clever and complex construction of shifting timelines. Corroded by grief, frustration and fury, Nesbitt was mesmerising.

At the end all we wanted to know was whether Oliver was dead or alive. Until the very last scene we assumed it was the former, though no visual evidence was ever given. I had tears rolling down my cheeks as his mother made a heart-rending speech at her second wedding, underlining the need to look to the future while never forgetting the past. She was drawing a line. And so were we emotionally shattered viewers.

But then came the chilling climax, as a half-crazed, dirty and unkempt Nesbitt was shown staggering through a frozen Russian town, banging on doors in search of his lost boy. As a youngster who looked like an older Oliver answered the door, Nesbitt was dragged away screaming by police.

A teaser trail appeared for the next series. But it was for an entirely different storyline so we never know the true fate of Oliver and his devastated dad.

Then there was the ending of The Fall. The dark serial killer drama already had form on the infuriating finale front. We all thought Gillian “Stella” Anderson would nail multiple murderer Paul Spector (played by Jamie Dornan) at the close of series one. But the producers were probably hanging on for a call from their commissioning editors. The cliffhanger is often more to do with securing another series than dramatic tension.

In its second incarnation, The Fall had another exasperating conclusion. The serial killer had led Stella to his last victim, who was hovering between life and death. Then the killer got shot by the side plot gangster. “We’re losing him” was the final phrase from Stella but we never knew if he really did expire. Nor his victim for that matter.

But if there’s one series finale that outraged its fans so much they actually launched a petition to get it remade, it’s Game of Thrones. I came late to this leviathan of popular culture but once hooked I binged 50 episodes in a fortnight.

Dismissed by some as high-budget dungeons and dragons, it was so much more nuanced than that – from a portrayal of human relationships that would disturb even Freud to its dissection of power and how the pursuit of it can send anyone’s moral compass spinning.

Yes it had zombies and a sorceress who produced something truly alarming from her nether regions but many of its plots were rooted in reality with parallels in history. The warring families of Lannister and Stark instantly called to mind the rival houses of Lancaster and York in the War of the Roses.

It had fabulous female characters, terrifying villains and it looked incredible with £7m per episode lavished on CGI and some of the most spectacular locations on the planet. Based on the fantasy books of George RR Martin, its narrative structure was dazzling as individual storylines were interwoven into the one big vivid tapestry of the fight for the throne.

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So after eight seasons, when its final episode was screened in May 2019, viewers across the globe were poised for the biggest televisual climax of the 21st century. I was one of them, staying up until 3.00am to watch the livestream in a living room lit only by the glow of pillar candles to give it that medieval epic vibe.

But rather than the anticipated blaze of glory exit, Game of Thrones was snuffed out like a damp match. The warning signs were there that the climax would be somewhat rushed and premature. The producers had run out of source material – George RR Martin still had two volumes to write for his book series “A Song of Ice and Fire” upon which the show was based.

So they basically made up another ending which killed off two kickass Queens, exiled everyone’s favourite throne contender Jon Snow and crowned the series’ least interesting character Bran Stark King of the Six Kingdoms.

After eight seasons of intrigue, spectacle, blood-soaked carnage and more twists and turns than the A470, Game of Thrones fizzled out with Boring Bran chairing his court with all the drama of a county council planning committee.

Two years later the GoT faithful still haven’t got over it. A fortnight ago, a single tweet – teasing “Winter is coming” – from the show’s official Twitter account raised hopes that they may yet get their alternative ending (though it’s far more likely to be marking 10th anniversary repeats.)

But, just as in real life, sometimes you simply have to move on. Or reflect on a lack of closure with a new clarity. So a week after Line of Duty’s much-maligned conclusion I’ve started to wonder whether it really was such a disappointment.

After all, there were satisfying moments. The duping of the boot-faced guards who made Prisoner Cell Block H’s Vera “Vinegar Tits” Bennett look like Nanette Newman was deeply gratifying.

Kate and Steve resumed their platonic mating ritual while Jo Davison’s new life in witness protection seemed to be a particularly glamorous episode of Escape to the Country, complete with obligatory Golden Retriever. Terry Boyle’s rehoming, meanwhile, was genuinely moving.

And they didn’t kill off Hastings. Mother of God, a dead Ted would have been more than anyone could bear.

But most of all there was the sense that the real drama lies in the horribly mundane not the car chases or gun duels. Jed Mercurio is a writer who always makes us look beyond the small screen to the bigger picture. From Jimmy Savile to the death of Stephen Lawrence, real-life crime and cover-ups echoed through the plots of Line of Duty.

From politics to policing, institutionalised corruption in the real world is not the work of a single evil genius, it’s a collective act of people like Buckells failing upwards, lacking conscience and looking the other way.

For six seasons Line of Duty has gripped and entertained. A definite – or even definate – conclusion would have left its fanbase content and sated.

Yet perhaps Mercurio, like all great dramatists, has a higher ambition for his art – to make his audience think and reflect far beyond the closing credits. What better way to show us there is no end to corruption than giving us no real ending.