Image caption L to R: Line of Duty stars Vicky McClure, Adrian Dunbar and Martin Compston

More than nine million viewers tuned into the final episode of Line of Duty on Sunday, giving it the biggest overnight audience of 2019 so far.

The tense conclusion to the BBC One drama's fifth series attracted an average audience of 9.1 million, according to overnight figures.

Charlotte Moore, the BBC's director of content, said it was "fantastic to see such a big audience" for the show.

Critics said the episode was "breathtaking" and "deeply satisfying".

Yet some expressed reservations about the series as a whole, saying it has been "lacklustre" and the "weakest" to date.

The BBC has already commissioned a sixth series from writer Jed Mercurio, who also wrote Bodyguard.

Line of Duty's figures are the highest for a drama since last year's Bodyguard finale, which drew an overnight audience of 10.4 million last September.

ITV's royal drama Victoria, which went out at the same time as Line of Duty on Sunday, attracted an average audience of 2.5 million.

Do not read on if you do not want to know anything else about Line of Duty's final episode.

Viewers on Sunday saw Ted Hastings (Adrian Dunbar), head of anti-corruption unit AC-12, interrogated at length by his superior Patricia Carmichael (Anna Maxwell Martin).

The result, said the Telegraph's Allison Pearson, was "an extraordinarily tense scene, a remarkable piece of theatre and one of the best things anyone will see this year on a TV screen."

The Times' Carol Midgley said the scene was "forensically written and beautifully executed", while Jan Moir from the Daily Mail called it "beautifully scripted".

Moir also praised a "killer twist" at the conclusion of a "nerve-shredding" episode that kept audiences "guessing right until almost the end."

Image caption Anna Maxwell Martin returned as Patricia Carmichael in Sunday's episode

"The latest twist was a classic Line of Duty curveball," wrote the Mirror's Ian Hyland - albeit one that "stretched credibility to breaking point."

The Guardian's Lucy Mangan said it was "as deeply satisfying as any in AC-12's history" but said the series as a whole had "felt like a placeholder season".

"The twists are getting dafter but Line of Duty remains crazily compelling," wrote Mike Ward in the Express.

The Independent's Ed Power, meanwhile, said the "exceedingly talky" episode "wrap[ped] up most of its loose ends... with excessive leisureliness."

'Ballsy confidence'

Twitter users have also had much to say about the episode, with praise being shared between the writing and its actors.

"The writing talent and sheer ballsy confidence of Jed Mercurio is breathtaking," wrote broadcaster Muriel Gray, going on to salute the "outstanding" cast.

The BBC's Dan Walker was particularly impressed by one scene featuring actors Vicky McClure and Martin Compston.

The British Transport Police also got in on the action, insisting its recruitment processes were "much better" than the ones depicted in the show.

In her own Twitter post, McClure gave "a huge thank you to the LOD family for making this such a special series."

"Behind every good cast there's a phenomenal crew," wrote Compston. "To make this show really is a team effort."

The credits for the 85-minute episode ended with a tribute to Graeme Livingstone, a crew member who died in a motorcycle accident in 2017.

The first episode of this series of Line of Duty drew an overnight audience of 7.8 million viewers when it aired at the end of March.

That figure rose to almost 11 million once the number of people who watched the show on devices was taken into account.

Figures for the Line of Duty finale are also expected to grow once consolidated numbers are tabulated.

Follow us on Facebook, on Twitter @BBCNewsEnts, or on Instagram at bbcnewsents. If you have a story suggestion email entertainment.news@bbc.co.uk.