Who is H? We may still not know by the end of series 5 says 'Line of Duty' star

Don’t hold your breath to find out who Line of Duty’s “H” is in the series five finale on Sunday – one of the show’s stars has hinted that we may still be none the wiser by the time the credits roll.

Rochenda Sandall joined the current series as Lisa McQueen, one of the top criminals in the organised crime group that police corruption department AC-12 have been hunting.

But she has suggested that the identity of mysterious character “H”, thought to be the top crime boss and corrupt police officer instructing McQueen’s gang, may still not be revealed by the series end.

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The evidence has been mounting against Superintendent Ted Hastings (Adrian Dunbar), the gaffer of AC-12, and fans of the BBC series are keen to discover whether he really could be the most bent copper of them all or if, as he says, he’s being framed.

Sandall appeared on This Morning, but asked whether there would be a satisfactory conclusion to wrap things up, she said: “It will certainly have some form of conclusion but as you’re all aware there’s still another series to go.”

Host Phillip Schofield asked who “H” was, but she laughed: “I can’t tell you that!”

The star wouldn’t even be drawn on whether she knew who it was, replying: “Maybe I do, maybe I don’t.”

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She added: “My mum is desperate for an exclusive. Every week she rings and I have to tell her no.

“But a lot of people say, ‘Don’t tell me’, they like to keep it a surprise and play detective themselves.”

Sandall might not have spilled the beans on Line of Duty’s biggest secret, but she did reveal the stomach-churning truth behind one scene.

One of the other stars of the series has been Stephen Graham, who played undercover officer posing as a gang member John Corbett and was brutally killed off in a grisly closing scene of a previous episode.

But Sandall said that the murder had not been nearly as horrific as a run-in with a dodgy prawn curry they both ate before filming a scene where their characters got in contact with “H” using messages on a laptop.

She said: “We all started to go a bit pasty and sweaty. I said to Stephen, ‘Are you alright, mate? What did you have for lunch?’

“We realised we’d all had the prawn curry and it was like a domino effect between all the crew.

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“But you’ve got to keep it together with adrenaline and I was actually quite surprised that you couldn’t tell. Bless the make-up girls, they did an absolutely brilliant job to hide it.”

Line of Duty series five concludes with a special 90-minute episode on Sunday, May 5 at 9pm on BBC One.