How does it feel to be responsible for the death of Max Cunningham, one of the show's most iconic characters?
"I was gutted really because Matt [Littler]'s such a great guy and plays a great character. Ultimately, it's brilliant just to be part of it all. It's just sad to see him go. The episodes are some of the best material that I've done."
Is it all an accident?
"Completely. He wasn't aiming to mow anyone down. Across the whole of the wedding day, Niall's just distraught about Steph and feeling rejection in general. He never really gets anything that he wants and it's just a build-up of everything. His remorse is evident as soon as the accident happens."
It's ironic then, that the time when he does kill someone, it's not even a member of the McQueen family…
"That's what I really liked about the story. When Bryan [Kirkwood] was talking to me about it, I loved the fact that it's the first time he majorly oversteps the line. It also serves to set up his mental state for further on down the line.
Does Niall seize the opportunity to pursue Steph? Or is he not that insensitive?
"No, he's more concerned that she doesn't blame him for Max's death. He's always struggled with that. We all know Niall's a complete psycho, but in his head, he's not. He just struggles with anger and immediately regrets things as soon as he's done them.
And next week, it's Tina's turn to experience Niall's wrath…
"Tina's discussing the possibility of giving the baby away, so, from then on, Niall turns on her. It's exactly what happened to him when he was a child. Basically, she gets too high up some steps and unfortunately, the resident evil is stood behind her…"
I hear you're slowly running out of psychotic faces…
"Yeah. I have three in the locker. I've used two and I'm desperately trying to hold on to the last one for whenever my last episode is. I'm going to try and hold out as long as possible with the last one, but it's wearing thin. I've got variations of them both, though."
Do you practise them in the mirror?
"Oh, daily. I was born with an evil face."
If Niall's working his way through the McQueens, that must mean John Paul's next?
"Yes, definitely. Niall continues to plant seeds in everyone's heads to ensure things can happen. For example, Kieron tells Niall that John Paul's in bed for a couple of hours at the flat and asks him to wake him up if he's not up in an hour. Niall sees the wedding vows in Kieron's pocket and puts them in the bedroom next to John Paul. And when Kieron gets to the church and realises that he's forgotten his vows, he asks Myra to go and them up. Niall's behaviour has just turned childish now – he's like an adult David Platt but 100 times scarier. He's got that same kind of annoying 'boy thing'. He's just attention seeking."
How far off is the reveal of Niall's true identity? Have you filmed that yet?
"No, we've not even had the scripts through. I've heard so many rumours about the reveal, but we don't know anything. As soon as I got the part and started filming, all the McQueens were coming up to me and saying 'we can't wait for the reveal' and I didn't even know what was going on. All I know now is that everyone's going to be involved…"
Do you think Niall's slowly becoming irredeemable?
"A character like Niall, to make the impact that I'd like, has to go one way. That's the way I saw it from day one. I was honest and open and so was Bryan. I said from the outset that if they wanted to go for the character of Niall, they had to go down that path."
Surely there's only so much bad one character can do?
"Exactly. Niall's kind of on the borderline of ridiculous anyway. When I started, Bryan said to me 'you have to come and see me and say if you feel it's going too far'. We've tried as hard as we can to keep him within the bounds of reality. We know that it has to come to an end eventually. I don't know when that's going to be, but fingers crossed that we can ride the wave as long as possible."
Has he taken the bad boy crown from Jamie Lomas (Warren)?
"I don't think it's a competition between Jamie and I. Jamie plays his own style of villain and I have mine. I think that's what the producers wanted anyway – they didn't want another Warren Fox to come in. What they wanted from Niall was a different kind of villain. There's always been your out-and-out bad boys such as Warren; then you've got your evil, love-to-hate Clare Cunningham and when she left, Niall took her place. By the same token, when Niall leaves, I'm sure they'll bring in someone for Jamie to play alongside."