Fans were left unable to sleep after Line of Duty’s latest dramatic episode - as they tried once again to work out the identity of a principal character.

Thirteen million viewers watched the BBC1 crime thriller to see Martin Compston's character DS Steve Arnott be involved in a shoot out and car crash as the Anti Corruption team AC-12 tries to uncover the bent coppers in the force.

As the show ended it was revealed that DCI Jo Davidson played by Kelly Macdonald is a blood relative of someone found on the police DNA database.

And the cliffhanger drove everyone crazy as people rewound the show continuously on their televisions to see if they'd missed a vital clue.

Some viewers contorted themselves to take pictures of upside down files whilst others tried to check character's ages to see if they'd be old enough to qualify as a candidate.

As Steve Arnott continued to gorge himself on painkillers it appeared that viewers were also pained to reach any conclusions.

Even the BBC announcer for the show remarked: "I think we all need somebody to talk to now don't we?"

One person showed a still from the show of the upside down file saying: "If AC-12 need another police officer, my mum is free and very good at detective work #LineOfDuty."

Another replied: "This is exactly what we did last night, couldn’t get to sleep brain whizzing around, must say loving #LineOfDuty."

Someone else confessed: "Worst sleep ever last night. Brain full of #LineOfDuty theories. Weirdest dreams ever - even my subconscious is confused."

And another person added: 'Stayed up after work to watch last night’s #LineOfDuty and I’d like to know how I’m supposed to sleep now please?"

While another confirmed: Didn’t sleep v well because of Line of Duty. My brain hurts."

After looking more closely at the file in the end scenes, the photo looks like Jo.

This is perhaps because it is Jo, however it doesn't give us the answer unless she has a twin?

Of course it could be that the shared DNA belongs to her mother or sibling

Hastings exclaimed: "Mother of God" and some fans think the mystery person will be revealed to be John Corbett, the undercover cop played by Stephen Graham in the last series.

It could also be Tommy Hunter (Brian McCardle) who is also Scottish.

The other Scottish character is former Deputy Chief Constable of Central Police Mike Dryden (Mark Bonnar).

Either way , we hope to sleep tonight.

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