It's the end of days. HBO's daring series The Leftovers has aired its last episodes in the US, with the third and final season now going out on Sky Atlantic on this side of the pond.

On the surface, it's a series about those 'left behind' when 140 million people – 2% of the world's population – vanish without explanation. But it's actually about so much more: faith, morality, grief and acceptance.

"I'm very, very proud of what we achieved," says Christopher Eccleston, who plays Matt Jamison, a minister who struggles with what he believes to be God's rejection. "I do feel, in years to come, the reputation of The Leftovers will grow. Because we did not compromise, and that's all credit to Damon Lindelof and his team of writers, who did an extraordinary job."

With the final season underway in the UK, and the latest Matt-centric episode, 'It's a Matt, Matt, Matt, Matt World' airing later this month, Eccleston spoke with Digital Spy about being a part of The Leftovers and how he had to fight to be a part of the series.

The Leftovers is one of the longest-running TV projects you've been a part of. What kept you engaged and interested?

"The writing, as always with me, on television, and on stage. Not so much in film! But television and stage, it's always about the writing for me. I approached Damon Lindelof about the part. I heard that HBO had optioned the novel, The Leftovers, so I read it and got an audition for the lead role.

HBO

"They didn't want me for that, but then I asked to meet Damon, and he was intrigued. I spoke to him about Matt Jamison, who was not even gonna be in the series, and he was enthused by my take on Matt, and it grew from there, really.

"The character, I felt, from the novel, was begging to be used on television. Because at a time when something has happened that some people are interpreting as a religious event, he had not been chosen, so I thought that was a great character for drama."

You had one episode per season in which Matt was central. Could you pick a favourite?

"Impossible, completely impossible. I was very, very fortunate, not just with the scripts but with the two directors I got. First season, I had Keith Gordon, who bizarrely... I'd gone to a cinema in my early teens and seen a film called Christine (1983) in which he was the lead actor.

"That performance was one of the major influences on me becoming an actor, because he played this character... I suppose you would describe him as a nerd-turned-bully, and it was a beautiful performance of grey areas. So I had Keith for the first, and then for seasons two and three, I had Nicole Kassell (The Woodsman), and they were key for me. Great directors."

How do you see Matt as having evolved across the series? He undergoes a major shift in the final season...

"He is a very, very different man by the end of my episode this year. In season one and season two, and at the beginning of season three, he's fundamentally the same person. He's still very much a man of organised religion – dogmatic, obstinate and angry and driven, but not without empathy, not without care.

"He's a very complicated, contradictory character, who I loved playing. But what Damon gave me through the arc of season three was a complete and utter transformation. I believe when we leave Matt, he's in a much better place, spiritually, emotionally."

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No spoilers, but 'It's a Matt, Matt, Matt, Matt World' includes a memorable scene featuring a live lion. How was it filming that?

"[It was] beautiful. I wasn't happy seeing him caged, to be honest. I wasn't happy about the existence that lay before him, I have to be honest about that. I would've seen him out of the cage.

"He scared the shit out of me during one take! Suddenly, during one take, I think he decided that I was edible. He let out this snarl and I jumped about six foot in the air! I know they got it on film. I've not seen my episode yet. I'm not a great one for watching myself. But I will watch it and I'm hoping that take is included, 'cause it was very real."

With The Leftovers being an ensemble show, how did you feel about Matt playing a major part in some episodes and factoring less into others?

"It was very much the experience that I was trained for at drama school. It's a theatre approach, really, and HBO and Damon were very clever, because what they did was they cast largely theatre actors – from Boston, Chicago and New York – so people who were used to an ensemble approach.

"We had no stars or supermodels or anything like that. Our leading man, Justin, has really earned his stripes, he's paid his dues – off Broadway, on Broadway. He's come through a theatre tradition... and that's how we worked.

"I was aware of no jealousies, no in-fighting, everybody got their chance and everybody was supported. And they're friends for life, for me. And I think you see that on-screen, in terms of the chemistry. Myself and Justin and Carrie [Coon] and Ann Dowd and Amy [Brenneman]... everybody really. It was a very positive experience."

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The Leftovers was, in particular, a breakthrough project for Carrie Coon. How was it working together with her?

"Well, the first time I met Carrie was on the pilot, which we shot 3-4 months before we shot the first series and it was an incredibly hot day in upstate New York and we exchanged books, actually. I remember giving her Stoner, a book by John Williams, a kind of rediscovered classic, which she loved.

"We talked mostly through books, me and Carrie. And at that point, we had absolutely no idea that we were gonna become brother and sister, and I'm not sure when that innovation happened, because they're not brother and sister in the book.

"It was great to watch her career take off like that. She was humble with it, and modest, and down-to-earth, and again that comes to the fact that she spent years struggling, and she spent years in theatre. Very, very intelligent, very level-headed and very bold actor."

The series relocated each year – from New York in season one, to Texas in season two, to finally Australia in season three. What was that experience like?

"We became nomads on The Leftovers and I think it's very unusual for an American series to show that there is a world outside America, so I'm very proud of that as well. It's a very unusual show that will take these characters and say, yes, they're American, but they're also human beings and members of the world community, and here they are in the Outback. I loved it."

The series finale, 'The Book of Nora', has gone out in the US – were you satisfied with that last episode and the react to it?

"I though what Damon Lindelof had done was quite, quite brilliant. Damon Lindelof's interesting, because he goes down in history, certainly in some people's eyes, as the man who wrote the worst finale of all time, with Lost. Now he goes down, also, as the man who wrote the greatest finale of all time.

HBO

"I was just very pleased for Damon, because that Lost business did hurt him. He invests hugely, emotionally, in the programmes and the films that he makes and he's a great fella, he's a really lovely bloke, so I was pleased for him most of all, and the team of writers.

"It's no secret – we were not particularly well-reviewed, or viewed, in series one. The reviews were extraordinary for series two, but we still didn't find a mass audience, and with series three, we've still not found that mass audience but the reviews have become even better. I've never been involved in a project that has been reviewed this well."

Despite all he's lost – his wife, his son – Matt's faith in God has been unwavering up till the final episodes... why do you think that is?

"Well, that is kind of explained in my episode this year, and it is my belief that religious figures, in the end, it's about their own ego. They value what they regard to be their special relationship to God as being central to their identity.

"It's about 'Somebody is watching and look how virtuous I'm being' – so it's ego and it's arrogance, and he has to shed that. I think truly spiritual people do. He should've been a Buddhist, let's be honest, old Matt. Maybe he is now, maybe he is!"

The Leftovers continues on Tuesdays on Sky Atlantic. 'It's a Matt, Matt, Matt, Matt World' will air July 25. The entire series is available now on Sky Box Sets.

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