'Line Of Duty': Who is Jo Davidson's mystery relative? All the best theories

Programme Name: Line of Duty S6 - TX: n/a - Episode: Line Of Duty - Ep 4 (No. n/a) - Picture Shows:  DCI Joanne Davidson (KELLY MACDONALD) - (C) World Productions - Photographer: Steffan Hill
Who is DCI Jo Davidson's mystery relative? (C) World Productions - Photographer: Steffan Hill

Mother of God! DCI Jo Davidson has a mystery relative whose identity is so shocking, we're going to have to wait at least another week until it is revealed.

Line Of Duty ended series six's most dramatic episode yet with a huge cliffhanger as AC-12 uncovered evidence that proved not only that DCI Davidson had been at Farida Jatri's house, but her DNA also matched a significant other person's who was being kept on file by the police.

Following a traumatic shoot-out between AC-12 and the OCG that left one officer dead, the anti-corruption unit are keener than ever to get to the bottom of whether Davidson is really a bent copper.

Read more: Line Of Duty viewers spot lift scene fail

But as DI Steve Arnott offered the fingerprint and DNA report from Jatri's house to Superintendent Ted Hastings, he pointed out the startling new finding that Davidson had a match in the system.

He said: "There's only one credible explanation for Jo Davidson's DNA matching this individual. They're blood relatives.

"He's identified over the page."

Who is? We'll have to wait until Sunday to find out, but in the meantime we're mulling over the suspects for Davidson's family tree.

Superintendent Ted Hastings

In an early episode of series six, a framed photo at Davidson's home showed her with just her mother – no father in sight.

Could Hastings's "Mother of God!" exclamation be due to him discovering that she is actually his daughter?

WARNING: Embargoed for publication until 00:00:01 on 30/03/2021 - Programme Name: Line of Duty S6 - TX: n/a - Episode: Line Of Duty - Ep 3 (No. n/a) - Picture Shows:  Superintendent Ted Hastings (ADRIAN DUNBAR) - (C) World Productions - Photographer: Chris Barr
Could Hastings be Davidson's father? (C) World Productions - Photographer: Chris Barr

We've previously discovered that Hastings had a relationship with Northern Ireland police informant Anne-Marie McGillis many moons ago, who turned out to be DI John Corbett's birth mother.

Perhaps Corbett wasn't the only child McGillis had to give up for adoption?

DI John Corbett

If Davidson is a DNA match for both Hastings and Corbett, that is one serious "Mother of God" discovery.

Corbett was under investigation in series five after being embedded in the OCG and toeing a fine line between police work and crime.

Stephen Graham will play the leader of the Balaclava Men in 'Line of Duty' series 5. (Credit: BBC)
Stephen Graham as John Corbett (Credit: BBC)

He was eventually killed off by the OCG's Ryan Pilkington, who is now serving in Davidson's police team and is blackmailing her to keep him on staff.

One of the big reveals of series five was that Corbett's birth mother was Hastings's old flame McGillis, and the undercover detective's legacy has lived on in series six with his widow Stephanie featuring heavily – both in phone calls to Hastings and by growing closer to Arnott.

Could there be another reason Line Of Duty refuses to lay Corbett's memory to rest just yet?

DI Steve Arnott

WARNING: Embargoed for publication until 00:00:01 on 30/03/2021 - Programme Name: Line of Duty S6 - TX: n/a - Episode: Line Of Duty - Ep 3 (No. n/a) - Picture Shows:  DI Steve Arnott (MARTIN COMPSTON) - (C) World Productions - Photographer: Steffan Hill
Arnott could be the relative (C) World Productions - Photographer: Steffan Hill

It's one of the more unlikely theories, but it would certainly be a shock to everyone involved if Davidson and Arnott turned out to be related.

They've been pretty sour with each other so far as they clash over AC-12's investigation of Davidson's team and DI Kate Fleming's divided loyalties to both of them, so it would make for a juicy twist.

Arnott and Davidson are similar in age so there's a possibility they could be siblings, although it seems slim, with no suggestion of long-lost family on Arnott's side and nothing in common about where they were brought up.

Tommy Hunter

Late OCG boss Tommy Hunter is the prime suspect, partly because both he and Davidson are Scottish, and partly because there's probably no one worse for a detective to be found to be related to.

Hunter was terrorising various members of the police way back in series one, including bent copper Dot Cottan, who killed him off in series two when he became a police informant.

The crime boss had also been the head of a paedophile ring whose high-profile members are still giving AC-12 cause for concern and whom murdered journalist Gail Vella, whose death Davidson's team are investigating, had been looking into.

Davidson has tried to claim she has no close family, but there's a good chance Hunter, 14 years her senior, could have been part of her extended family. It would explain how the OCG are blackmailing her.

Terry Boyle

WARNING: Embargoed for publication until 00:00:01 on 30/03/2021 - Programme Name: Line of Duty S6 - TX: n/a - Episode: Line Of Duty - Ep 3 (No. n/a) - Picture Shows:  Supporting Artist, Ryan Pilkington (GREGORY PIPER), Terry Boyle (TOMMY JESSOP) - (C) World Productions - Photographer: Steffan Hill
Terry Boyle features in series 6 (C) World Productions - Photographer: Steffan Hill

The OCG's favourite fall guy has had a rough time in series six – not only has he been framed for Gail Vella's murder, but the crime gang's police plant Ryan Pilkington also tried to bump him off by driving him into a lake.

Little has been said about Boyle's family and Davidson has been very careful not to push Boyle too hard whenever he's been brought in for questioning.

Read more: Who is Terry Boyle and what's the significance of his freezer?

Fleming interpreted this as her boss allowing the OCG to pin the murder on him by not pressing hard enough for details of who really did it, but could a different explanation be that she doesn't want to upset a secret brother or cousin?

It would also make Davidson an easy target for OCG corruption if they thought she needed to protect Boyle.

Superintendent Alison Powell

Series five was a tangle of corrupt officers, divided loyalties and questionable police decisions, with Superintendent Alison Powell at the head of them.

Powell was Corbett's boss and was under suspicion by AC-12 for withholding files from an investigation, before eventually admitting that their OCG suspect Corbett was actually her undercover officer who she had lost contact with.

As Arnott got to know Corbett before his murder, he revealed that he and a colleague had started to suspect that Powell was directing investigations away from high-level OCG activity and distracting the police with their smaller crimes.

WARNING: Embargoed for publication until 00:00:01 on 16/03/2021 - Programme Name: Line of Duty S6 - TX: n/a - Episode: Line Of Duty - Ep 1 (No. n/a) - Picture Shows: *NOT FOR PUBLICATION UNTIL 00:01HRS, TUESDAY 16TH MARCH, 2021* DCI Joanne Davidson (KELLY MACDONALD), DI Kate Fleming (VICKY MCCLURE) - (C) World Productions - Photographer: Steffan Hill
Does DCI Jo Davidson have something to hide? (C) World Productions - Photographer: Steffan Hill

If Powell is the mystery relative, she could have forced Davidson's assistance – although it looks unlikely as Arnott seemed to suggest the DNA match was male.

DCC Mike Dryden

Line Of Duty fans have been trawling the old cast lists for Scottish characters as likely secret relatives, and one name that has been thrown up is the former DCC Mike Dryden.

The ex-high-ranking officer is currently serving a prison sentence for perverting the course of justice as he lied about an alibi for a night when he was having sex with a teenager that linked him to a sex scandal.

Read more: Test your Line Of Duty knowledge with our quiz

He also had an affair with DI Lindsay Denton and featured heavily in her storylines, but while he isn't exactly a relative to be proud of, there's no obvious reason that Davidson would want to hide a link.

ACC Derek Hilton

The late ACC Derek Hilton was one of the main suspects as crime orchestrator H and also happens to be Scottish, just like Davidson.

He was framed as having committed suicide, although it looks more likely to have been an OCG murder, after DCI Roz Huntley gave evidence that he had ordered one of the Balaclava Men to throw Arnott down the stairs.

While it may partly explain Davidson's huge animosity towards Arnott and it would certainly be a strange coincidence if they were related, again there's no real reason she would have hidden it.

Lee Banks

Remember OCG heavy Lee Banks, who carried out a number of murders for the gang?

He eventually went to prison and was last seen being visited by Hastings, who had some mystery information for him – that is, until the end of the most recent episode when he was shown strangling Jimmy Lakewell to death in his cell for being a rat.

Programme Name: Line of Duty S6 - TX: n/a - Episode: Line Of Duty - Ep 4 (No. n/a) - Picture Shows:  DI Kate Fleming (VICKY MCCLURE), DCI Joanne Davidson (KELLY MACDONALD) - (C) World Productions - Photographer: Steffan Hill
DI Kate Fleming is now working for DCI Joanne Davidson. (World Productions/Steffan Hill)

Ryan Pilkington later shared the news with a clearly horrified Davidson, warning her off revealing any information of her own, and it seems likely Lee is related to Gail Vella murder suspect Carl Banks.

However, the only real reason for suspecting Davidson is also in the family is to explain his reappearance in the show – although it would explain her trying to throw the investigation away from Carl's direction.

Tim Ifield

Forensics officer Tim Ifield featured in the most shocking opening episode ever to a Line Of Duty series when DCI Roz Huntley woke up to him wielding a power saw above her head as he planned to dismember her body, believing he had accidentally killed her.

The tables were turned when she fought back and ended up killing him instead, spending a whole series trying to get away with it but eventually ending up jailed for 10 years.

Huntley's solicitor husband turned out to be entangled in the OCG drama, so if Davidson is related to Ifield there could be a tenuous link to a revenge plot on behalf of her relative.

Watch: Line Of Duty series 6 teaser