IF The Walking Dead was a motor vehicle, it would be a huge American juggernaut, spattered with mud and zombie guts, and completely unstoppable.

Since its debut in autumn 2010, the show, based on the comic book series, has seen viewing figures triple in the US, been nominated for a clutch of awards and has even spawned a spin-off, Fear The Walking Dead.

Though its audiences have never been huge in Ireland, it does have a hardcore following of extremely dedicated fans in this country.

Understandably, plot lines are a closely guarded secret — British star Andrew Lincoln even made his mum sign a non-disclosure agreement after he told her a massive spoiler (more of which later) — and fans take to the internet to dissect every last twist.

It’s currently back on Fox for Series 6 Part B, which sees a new threat to Sheriff’s Deputy Rick Grimes (Lincoln) and his band of survivors, in the form of psychopath Negan (Jeffrey Dean Morgan) and the Saviours, who fans of the comics will already know are pretty mean.

Lincoln and his co-stars Michael Cudlitz (Abraham) and Ross Marquand (Aaron) reveal what we’ve learned from the show so far...

THEY’RE SURPRISED BY THE SUCCESS

Before The Walking Dead, Andrew Lincoln was best known for that silent declaration of love to Keira Knightley in Love, Actually and as Egg in cult 1990s drama This Life. Now, he can’t leave home.

“It is bad, yeah, it’s crazy — it’s gone nuts actually. I don’t go out that much any more,” he says, with a coy smile.

“We were happy with one season. We all sort of linked arms, jumped off a cliff edge and hoped the parachutes would open — and it seemed to work. Every season I go into it not anticipating what will happen, and it’s just blown out of all proportion. I mean, it’s crazy, this journey.”

RICK AND MICHONNE’S KISS WAS A BIG DEAL

Fans had been hoping for it for a long time — and now Rick and samurai sword-wielding Michonne (Danai Gurira) have finally locked lips on screen.

“My mum had been campaigning for quite some time for this to happen. I told her when she came out to visit in Atlanta,” reveals Lincoln.

“I said, ‘I think you’re going to be happy at the back end [of series six]’ and she went ‘No!’ and I made her sign a non-disclosure agreement.

“I think it’s a great moment, but Danai was behaving quite weirdly. I hadn’t read the episode [yet], and she came on set and started getting really shy and strange around me. I read it and screamed, banged on her trailer and said, ‘What the heck?’ They were talking about doing the kiss the first day of that shoot and I said, ‘Please, come on, give us a few days just to get used to the idea’, because it’s a huge shift in their relationship, but an important one and a great one I think.”

THEY’RE A TIGHT-KNIT FAMILY

Cudlitz, who joined the Georgia-based show full-time in series five as Sgt Abraham Ford, says: “The guys who were here from the beginning set the tone for everyone coming in, and the energy couldn’t have been better.

"Andy and everyone all reached out by email before anyone had even arrived on set just to say, ‘Welcome, if you have any questions...’

“We’re all away from home, so we become our immediate family and it’s very supportive.”

LINCOLN’S NOT BORED YET

“I’ve never lived with a character for six years,” says the 42-year-old father-of-two.

“It’s a crazy experience and if it weren’t for the collaboration between all of these amazing ensemble actors, and crew... It was always pitched to me that we’d start in one place and everybody changes because of the environment.

"So it’s never felt like the same show, which is a great thing — and I’ve never had that, it’s not a procedural drama. I love it.

"I’m getting through most of the [Screen] Actors Guild of America in this show, I mean I’ve killed most of them... I’m hoping that in 12 more years, I’ll have worked with everybody.”

NEGAN IS MORE BADASS THAN THE GOVERNOR

Lincoln confesses: “I was trying to work out what’s the difference between Negan and The Governor [played by David Morrissey from series three] — and I think there’s something incredibly unapologetic about [Negan’s] psychopathy.

"Whereas The Governor was trying to pretend he was an ordinary dude and going about his business with severed heads in his basement, this guy just doesn’t care.

"And The Saviours are an incredibly organised and ruthless outfit, something that we’ve never seen before, so yeah, I think he’s more than a match for Rick and perhaps, I think, that may shock the survivors.

"Have I given away the rest of the series?...”

RICK BEING A DAD WAS KEY FOR LINCOLN

“I’m excited to see how the audience responds [to how the father-son relationship develops],” says the actor. “Whatever people think about it, Carl [played by 16-year-old Chandler Riggs] is a child soldier, but he’s also my son — in the comic books there’s a very interesting triangle with Negan, this strange respect between the two characters.

But always the thing that keyed me in to playing Rick was that relationship, the fact that he was a father first.

Chandler Riggs has done an amazing job of playing this character, and watching him grow up on screen has been a huge privilege. He’s now got more facial hair than Norman Reedus [who plays Daryl].”

THEIR FANS ARE THE BEST

The reason audiences love the show so much is because they can identify with the ethical dilemmas constantly facing the characters, believes Ross Marquand, who joined the cast as its first openly gay character Aaron in series five.

“It’s the most amazing thing, when you go to these conventions, people all say they have their favourites, and that’s a wonderful thing. People around the globe can see themselves in these characters, and that’s why they can have these conversations with friends about how they would personally react to a zombie apocalypse.

“It’s fascinating to see just how much this show, which, on the outside, seems just like a genre show about zombies, is actually tapping into something more human. People are loving it universally and it means something to them.”

The Walking Dead continues on Mondays at 9pm on Fox UK. Season six will be shown later this year on RTÉ2