The hit drama reached its season finale on Sunday and yesterday the BBC unveiled the sort of viewing figures which prove ‘event television’ has life in it yet

What is it?

Seriously? Where have you been? If you have to ask, it’s a long-running drama about AC-12, a police anti-corruption unit in an un-named British city. It stars Adrian Dunbar as AC-12 chief Superintendent Ted Hastings, and Martin Compston and Vicky McClure as his trusty detectives, DCI Steve Arnott and DCI Kate Fleming. Together they sniff out, track down, interrogate and then jail ‘bent coppers’, while all the time referring to each other as ‘mate’ and using a confusing lexicon of police terms such as ‘CHIS’ (covert human intelligence source’) and OCG (organised crime group). The sixth series has just finished and, as with most of the others, viewers have been absolutely gripped.

Why?

For a start, it’s written by veteran TV dramatist Jed Mercurio, who knows his onions – he was also the man behind Bodyguard, which had a similar appeal and generated similar viewing figures when it aired in 2018. Second, Line Of Duty has made part of its USP the casting of A-listers as guest stars. We were treated to Keeley Hawes in seasons two and three as Lindsay Denton (some LOD purists still think those were the best series) and she was followed by Thandiwe Newton (in season four), Stephen Graham (season five) and Kelly Macdonald (season six). Gina McKee, Lennie James, Daniel Mays and Craig Parkinson had all featured as well. A large part of the appeal is trying to guess the identity of the mysterious H, who may or may not exist and may or may not be a very high-ranking police officer up to his (or her?) neck in organised crime and corruption.

So what were the ratings like?

Enormous, frankly. Around 13 million of us tuned in for last night’s big finale, giving the show a whopping 56% of the UK TV audience. To put that in context, it’s the highest overnight audience figures for a drama since records began in 2002. In the era of video-on-demand, the overnight figures tend to be lower because people know they can watch on catch up services such as BBC iPlayer, but last night’s episode was unusual in that people wanted to watch it as it aired – and then take to social media to discuss it, of course. Referring to it as “addictive event television”, the BBC’s chief content office Charlotte Moore said: “Line Of Duty has kept the nation guessing for the last seven weeks, so it’s no surprise that last night’s jaw dropping finale set a ratings record.”

Did jaws drop?

Yes and no. Mercurio appeared to wrap things up by revealing who was behind the anonymous text messages which have been directing the various criminal enterprises over the last few series – it all hinged on a spelling mistake which was flagged up in the previous series – but whether that person really was H remains to be seen.

Will we find out?

Unlikely. It’s anticipated that there will be no more series made, though again Mercurio was a little cute here too – a lingering shot of brusque and not-entirely-trustworthy Detective Chief Superintendent Patricia Carmichael (Anna Maxwell Martin) certainly left the door open. Come to think of it, maybe she's H ...