Five huge questions we still have after last night's Line of Duty finale

Because we did not float up the Lagan in a bubble, you know

*Spoiler alert* – Do not continue if you're not up to date with the latest series of Line of Duty

Mother. Of. God. After five tense AF episodes, Line of Duty's fifth series concluded with a bumper 84-minute episode last night. Don't know about you, but we're still recovering from being on edge for the best part of an hour and a half.

It turned out Gill Biggeloe had been working with the organised crime group all along ('urgent exit required') and had been trying to frame Ted Hastings as H, as well as shut down AC-12 so that they could continue with their dodgy dealings in peace.

Poor John Corbett had well and truly been led up the garden path by Gill, who had convinced him Hastings was the reason his mother was killed in the eighties, and his vengeful undercover mission was just one big ol' wild goose chase.

The Beeb has commissioned a sixth series of Line of Duty, likely to air in 2021, so here are the questions we'll be trying suss out the answers to until then.

Who is the fourth officer in cahoots with the OCG?

'Who is H?!?!!' has been the question on the nation's lips since series 4. But last night it turned out there was more to Dot's dying declaration than we first thought – and thinking H was a person was the ultimate Jed Herring. (Thanks Steve.)

On closer inspection, the former caddy appeared to be tapping out the letter H in Morse code – four dots. 'H is not an initial. It's a clue,' confirmed Arnott. 'Four dots. Four caddys. Four police staff in league with organised crime.'

While Dot, Gill and Hilton have all been identified as working with the OCG, we're hoping we'll get to the bottom of the mystery of the forth person in series six – and that it's not one of the three musketeers, Kate, Steve or Ted. Because anything can happen on this show. Which leads us to...

Is Ted definitely not bent?

Or should that be 'definately'? Thankfully, the evidence suggesting our beloved Ted Hastings was H was proven to have been orchestrated by snakey Gill Biggeloe and he was reinstated, albeit on a final warning after his unauthorised undercover op.

Cut to the end of last night's episode though, and we see Hastings approaching the late John Corbett's wife with a suspicious looking package. The briefly mentioned missing £50,000, perhaps? It's all looking a bit shifty, fella.

Until we have clear confirmation of who the fourth OCG associate is within the police, we just can't trust that Jed won't betray us at the last minute.

Will Kate and Steve recognise Ryan?

'The person who made me see that there was another way, to be a useful member of society, was a police officer. He's the reason why I wanted to become a police officer too. To help people.'

The final grimly confirmed what we'd all feared ever since Ryan Pilkington's 'interview' was mentioned in episode four – that he has been working towards getting a place at police college, presumably so that the OCG can further infiltrate the force. The end montage showed what appeared to be a passing out parade with subtitles confirming he'd been accepted as a Student Police Officer. Yikes.

Ryan's links to the OCG when he was a child have clearly slipped through the net in terms of paperwork (remember when Kate interviewed him in series one?), but will the pair recognise him as the child who 'did the phones' and shouted 'bent bastard' every five minutes? We'll have to wait until the next series to find out what chaos the new caddy manages to cause within the police force.

What's the deal with Steve's pain pills?

Since the attack in series four that left him in a wheelchair, Steve has been dealing with lasting problems with his back, for which he's been taking pain meds and which seemed to leave him unable to perform in the bedroom with DS Sam Railston. (Awks.)

During the end montage, we were rather ominously shown Steve taking yet more pills before stashing them back in an overhead cupboard, foreshadowing a drug problem further down the line.

Don't know about you, but we're a little bit worried this could open Steve up to being blackmailed by the OCG in future...

Will we see more of Patricia Carmichael?

With her ice cold deliveries and seemingly unflappable manner, Anna Maxwell Martin managed to make DCS Patricia Carmichael one of the most infuriating characters ever. Far too smug about our Ted's demise, she was.

Of course, it was all alright in the end because the evidence against Ted was disproved (hooray!). But Carmichael was so hell bent on proving to everyone that Hastings was corrupt, that we got more than a whiff of a vendetta there. Something tells us that episode wasn't the last we'll see of her...

Line of Duty Series 1-5 is available now on BBC iPlayer