Line of Duty series 5 finale: Was THAT key piece of evidence there all along?

• Line of Duty series four: Who was Matthew "Dot" Cottan and why is his dying declaration so important?
• Meet the cast of Line of Duty series five
• Line of Duty series 5 episode 6 finale – live blog

We took a look back through some old episodes of Line of Duty to find the answer...

Was Dot's hand tapping in the original footage of the dying declaration?

Series three: At the end of series three, as DI Dot Cottan (Craig Parkinson) lay dying on the ground, DI Kate Fleming (Vicky McClure) moved in with her smartphone to record his "dying declaration".

The only word we could make out at this point was "Fairbank", before the cameras pulled out to reveal the wider scene of chaos. But in the final seconds of the episode, we learnt that Dot's dying declaration had helped get child molester Fairbank sent to jail for ten years.

It was only towards the end of series four that we saw (and heard) any more of that dying declaration.

Series four: In episode five, when ACC Derek Hilton (Paul Hilton) got hold of the video evidence and showed it to Superintendent Ted Hastings (Adrian Dunbar), it became clear that there was more to Dot's final moments. The footage had been pulled from one of the armed firearms officer's bodycams, and showed Kate trying to coax "The Caddy" into revealing the name of the senior police officer he was ultimately working for.

She asked him to "blink twice for the first letter of his name." He blinked twice for 'H' – at which point medics ordered Kate to stop: "That's it, out of the way. I'll start bagging. Respiratory arrest." Kate sat back on her heels, and this was the last frame before Hilton paused the video:

Series five: The footage DS Steve Arnott (Martin Compston) shows Kate and Ted at the very end of the series five finale is actually from AFTER the point we saw in series four. i.e., this particular section of the footage has never been shown to Line of Duty viewers before.

In the video, Kate has stopped taking Dot's dying declaration and is sitting back while the medics try to save him. But the AFO's bodycam is still recording, and even though he’s in respiratory arrest and can no longer speak, it seems Dot was still trying to communicate. Luckily, the bodycam recorded the moment his left hand began to move.

"Now, the frame it was frozen on during your interview made me spot something we've all missed," Steve says. "Look at Dot's left hand. Dot was trying to tell us something before he lost consciousness. He couldn’t speak due to the gunshot wound to his chest, but he could move his hand."

"Tap tap tap tap. Tap tap tap tap," says Kate. "It’s Morse code. Dot dot dot dot."

Steve explains: "The letter H in Morse code is four dots. ‘H’ is not an initial, it’s a clue. Four dots. Four caddies. Four police staff in league with organised crime."

Kate adds: Dot. Hilton. Gill. Plus one more..."

Did Craig Parkinson re-film his dying declaration?

So far, we are not 100% sure whether this section of the footage was filmed during series three and then secretly kept on file (which would have required Jed Mercurio to think really, really far ahead), or whether he called Craig Parkinson back in to recreate the moment of Dot Cottan's death during production for series five.

But Martin Compston did share this teaser photo of a (very bearded) Craig Parkinson...

• For the latest news and expert tips on getting the best deals this year, take a look at our Black Friday 2021 and Cyber Monday 2021 guides.

And Jed Mercurio shared this photo of The Caddy on set with series five guest star Stephen Graham.

Did they shoot some extra footage for series six? (And if so, what did they do about the beard...?)