Line Of Duty is known for being lots of things – tense, dramatic, complicated and thrilling are among just some of them.

One thing it’s never usually described as though is funny, but that changed on Sunday night thanks to some saucy messages it was revealed DSU Ian Buckells had been sending. 

The Hillside Lane boss was brought in for questioning at AC-12 HQ during the latest episode of the hit BBC drama, after mounting evidence pointed to him being corrupt. 

As part of their interrogation, AC-12 outlined how Buckells had previous contact with a witness that had come forward with information in the case of journalist Gail Vella’s murder. 

They then presented him with some rather embarrassing messages from his phone history that revealed he’d engaged in a bit of saucy chat with Deborah Devereux. 

In the texts, Deborah had asked him if he would show her his “trunshon” [sic], before he suggested showing her his “helmet” too. 

Needless to say the double entendres had viewers in stitches… 

Sunday night’s episode also saw the return of some other faces from Line Of Duty’s complicated past when slimy solicitor Jimmy Lakewell was revealed to have spoken to Vella about police corruption prior to her death. 

After he survived an attempt on his life during an ambush of a police convoy, he was later murdered in his prison cell by another returning character Lee Banks – a member of the OCG who has some history with Superintendent Hastings. 

The episode also revealed that MIT boss DCI Joanne Davidson is related to someone already known to AC-12 after a DNA sample of Davidson’s found at PS Farida Jatri’s house was a match for “a nominal” (aka a non police officer) already on their database. 

And while we face an agonising week’s wait to find out their identity, fans already have a (very plausible) theory as to who they might be.

Line Of Duty continues on Sunday at 9pm on BBC One.