Line of Duty, season 6 episode 7 review: the mystery is solved – and he fooled us all

Finally, the mystery is solved. And if you guessed it right, you deserve a Ted Hastings commemorative mug. For six long series, we’ve been looking for a criminal mastermind, the puppet master who has controlled a vast network of corrupt police officers. And when the big reveal came, I’d have been less surprised if it turned out to be Ted’s wee donkey. Dept Supt Ian Buckells, the blundering fool, had conned us all.

The lead-up to this moment involved misdirection (was it going to be Fairbank?) and a prison van ambush (yep, another one, though this had a good twist) and then a masterful sequence in which our man was led into the interview room. We glimpsed him walking by in handcuffs, we saw the back of his prison uniform, we waited for Steve Arnott to type his name. And then surely the longest beep from the DIR (digital interview recorder, but you probably know that by now). It was genuine edge-of-the-seat stuff.

Nigel Boyle as Buckells has been the stand-out performer of this series, and in this interview he was terrific. There was a great moment in which his expression changed, from looking dumb to looking smug: “I’m a blundering fool? I’m only the one who’s made total mugs out of you lot." Of course, he didn’t get the upper hand. As Ted Hastings told him, in a line that Adrian Dunbar delivered with relish: “No one makes mugs of AC-12.”

But did this finale leave behind a nagging feeling that writer Jed Mercurio had made mugs of the viewers? There was no H. Buckells was no kingpin. Instead, he was just the last man standing from a motley collection of middle-ranking detectives, and his motivation turned out to be a nice gaff in the country and a timeshare in Gran Canaria.

The 10 minutes that followed Buckells’s unmasking felt drained of energy. Ted confessed his wrongdoing to Patricia Carmichael (Anna Maxwell Martin, who has perfected the art of acting this role with just a twitch of the eye and a pursing of the lips). There was some business with the man from Occupational Health, who seemed to be a tougher interviewer than anyone from AC-12. And Chief Constable Osborne on TV again, lying through his teeth about the absence of institutionalised corruption and praising a breakthrough in the Gail Vella case. A word here for Andi Osho, who played Vella, and thus had a pivotal role while unfortunately being dead all the way through.

The friendship between Kate Fleming (Vicky McClure) and Steve Arnott (Martin Compston) has been one of the threads holding the show together, and there was a touching scene between them towards the end. Was there a hint of something more than friendship? I’d say he isn’t Kate’s type, but one of the wonders of Line of Duty is Steve’s ability to score with any woman who crosses his path. Nice one, mate.

It ended where it all began, with an image of Lennie James as Tony Gates, and the storyline came to a close. The BBC will be desperate for Mercurio to come back with a seventh series – the show has enjoyed the kind of monster ratings that broadcasters rarely see these days – but this felt like the right place to end it. Frankly, another outing in which they went after Osborne, or where DS Chris Lomax turned out to be bent, would be a series too far.

Maybe it has spin-off potential. How about giving a series to Chloe Bishop, surely Britain’s most competent junior detective? Or those two boot-faced warders would make good villains if they ever remake Prisoner: Cell Block H again.

I’ve griped about various bits of this show over the years – the jargon, the references to people and places we’d completely forgotten about, Steph Corbett’s Scouse accent, Thandiwe Newton’s septic arm – but it stands head and shoulders above most other dramas. It has kept up guessing and kept us talking. And it’s clever. To tie up a story this complex, leaving no loose ends, is a superb achievement. Perhaps the whole thing deserves to be rewatched from series one, with the knowledge we now have.

But, just to remind us that Line of Duty shouldn’t be taken too seriously, there was a truly hilarious coda. Joanne Davidson (Kelly Macdonald) living her best life in witness protection: a chocolate box cottage, tasteful Fair Isle knit, Boden catalogue girlfriend and a devoted golden retriever all included in the package. If this is what a life of corruption gets you, where do I sign up?

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