What was really going on in that Line of Duty prison murder scene? Lee Banks actor Alastair Natkiel explains

So what was really going on? Did Buckells order Jimmy's murder, and then get freaked out when he actually witnessed it? Or did the OCG order the murder, to warn Buckells not to cooperate with AC-12? Did Lee know who Buckells really was – or not? We got Mr Lee Banks himself on the phone to pick his brains.

"In my head, the way I always played it, is that none of us are ever quite sure [about Buckells being 'H']. But we might have a kind of an idea," Alastair Natkiel explained. "That scene is a bit of a red herring because, you know, Buckells was shaking in the way that he did, but obviously he would have known that it was coming.

"But I think what's clever about it is, there's all sorts of lines of communication. And there's ways and means of getting messages to me from the OCG. I think that they can get messages to me without having to come through Buckells. So I don't think that Lee – I don't know. It's a hard one! I'm not sure Lee would be 100% aware."

That said, there is unseen footage from season five which would have taken things in a slightly different direction: "There's scenes from the previous season that actually didn't end up in the in the final edit, which is the Stephen Graham character [John Corbett] asks me about H. And I said something like, 'Wouldn't you like to know?' But then that wasn't ever used, so that doesn't really count."

Whatever Lee knew (or didn't know) about Buckells, in some ways it doesn't matter. "He gets his orders. And he carries them out," Natkiel explains. "And I think that's the way that he's risen quite far up the ranks of the OCG because he's done whatever he's been asked to do. Whatever he's been told to do, he's done, no questions asked. He doesn't question the motives of why he has to do what he's ordered to do. He just goes and does it."

Natkiel also reckons that the order to kill Jimmy Lakewell came from the OCG, rather than from Buckells (even if Buckells had a heads-up that Jimmy was about to be murdered in his cell, hence the shaky hands and voice).

"Buckells is really, as he says in that final episode, just a messenger," says the actor. "He's not pulling the strings. He's literally just somebody who facilitates what needs to be done... and I don't need to take my messages from Buckells, because the OCG have got other ways – be it burner phones, or whatever it might be – of getting in contact with me, however they do that in the prison. The OCG's reach definitely goes wider than Buckells. So any orders that need to come to me, can come to me, without having to go through him."

The killing, he says, is a message directly from the OCG: "Obviously Buckells knows just as much as Jimmy, but we [the OCG] can't just get rid of Buckells because we need him. The OCG will know that. Jimmy, he's dispensable. So it is very much a warning, to just say: 'Keep your mouth shut.'"

Natkiel has played Lee Banks since season five, when he first appeared as a member of the OCG alongside Tomi May (Miroslav Minkowicz), Gregory Piper (the notorious Ryan Pilkington), Stephen Graham (undercover cop John Corbett) and Rochenda Sandall (Lisa McQueen).

Thanks to AC-12, he ended up behind bars mid-way through the season. And that, Natkiel thought, was probably that – until a gnomic remark from Jed Mercurio.

"I wasn't in the final two episodes of that season," the actor says. "And I was joking, just trying to have a bit of banter, saying 'Oh, I was expecting a big prison break or a big interview scene something.' And he just said, he said, 'Well, you're still alive.' That was all he said."

As for whether he really did expect to return for season six, he tells us: "I'm mates with Nigel Boyle, who plays Buckells, and he'd let me know he was going back into it. Obviously, we knew that Gregory Piper, who plays Ryan, was going into it because of the way that season five finished. Greg's character was being put into the police, so we knew that he'd be in it.

"I'd say I hoped more than anticipated. And to be honest, you know, the one thing that went through my mind really in terms of doubting whether I might be was that 'well, I'm in prison, so unless I get out of prison, there's not a lot of massive involvement I can have other than if they come and ask me for more information about what Hastings said to me in season five.'

"So obviously, when I got the call and read the scripts that I was going to come in and strangle Jimmy Lakewell, garrotte him by creeping up behind him – that was a bit of a shock."

That scene was filmed on the first day back after the COVID-enforced production shutdown. And there were no stunt doubles – only careful choreography, and plenty of run-throughs to work out who should throw their weight where (and when) to make the strangulation look realistic.

Of course, Natkiel's mate Nigel Boyle was there in the cell, too, with his shaky hands: "It was lovely to to get some screen time with him even if it was brief and vicious."

At this point, Boyle still couldn't tell anyone about Buckells' true identity – but he must have been desperate to share the secret. And after they both arrived at the hotel in Belfast where they were both separately quarantining, Boyle was desperate for Natkiel to read all the scripts.

"He said, 'Have you read the scripts?' And I said, 'No, I haven't actually, I've got to email production and ask for them and read them this week while I'm sat in the hotel room doing nothing.' And he was like, 'OK well, read them! Read them!'.

"And then the next time he messaged me, have you read the scripts? [I responded] 'No Nige I haven't! Give me a chance!' He was like, 'What episode are you on? I'm like, 'I'm on episode four.' He's like, 'OK, well keep reading, keep reading.'

"And then eventually, when I got to it, I was like, Oh my God!"

Natkiel has had a lot to keep under wraps ever since then, despite family and friends drilling him for info. For one thing, he couldn't admit that Carl Banks was Lee's brother until it was mentioned on screen. (In case anyone else was wondering: no, the actor whose picture was used for Carl is not, in fact, related to Natkiel in any way.)

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But that knowledge about Carl being his brother was necessary so he could "capture the anger that Lee's feeling" in that scene with DI Steve Arnott (Martin Compston): "Even though he's a cold-blooded killer, the death of his brother – it's not like he's got no emotion whatsoever."

That scene with Arnott brought with it a long-awaited payoff for another storyline: Lee Banks revealing what Superintendent Ted Hastings (Adrian Dunbar) told him off-screen in season five, when he dropped into Blackthorn Prison for a chat.

"“You want to talk about rats? Ask your boss," Lee told a stunned-looking Arnott. "He told me there was a rat in our crew. And that rat turned out to be an undercover copper. John Corbett."

It confirmed what we already suspected had happened – though Natkiel admits he was disappointed at first when he read the scripts for season five, and realised his big conversation with Hastings would be taking place off camera.

"As an actor, when I was reading that script, I was kind of – I read that little bit, and then I was reading through the next few pages, and I was waiting for the scene. And then I read the stage direction, we see Ted leaving the prison. And I was like – 'But where's the scene?'.

"And I was a bit gutted that the scene hadn't been written and that we weren't going to shoot it, and that the audience weren't going to see it... But Jed's obviously slightly cleverer than me, and he knew that actually by virtue of not seeing what had been shared, the impact of Ted's visit to Lee Banks was much higher."

It also made Lee's role pretty central to season six, given the information he was holding – and waiting to drop on Arnott's head, at the most dramatic moment possible.

So what next for Lee Banks? He is, as Jed Mercurio would point out, still alive. Perhaps in season seven he'll be wreaking havoc in Blackthorn Prison, or perhaps he'll get out of jail. All Natkiel can say is: "If there is another season – if that happens, who knows what he's thinking – but if that does happen, then Lee Banks is still alive and ready and raring to go."

Line of Duty seasons 1-6 are available on BBC iPlayer now. Take a look at the rest of our Drama coverage, or check out our TV guide to find out what's on television this week.