Charlie Hunnam is back on the big screen this week as he leads the cast in a quest to save the world in Pacific Rim.

The movie sees him team up with director Guillermo Del Toro while Idris Elba and Rinko Kikuchi are also on the cast list.

- So Charlie, you’re just saving the world this summer, huh?

You know, no big deal. Someone’s got to do it. [Laughs]

- Do you feel the weight of everything on your shoulders?

I did when I was wearing that suit that was kind of clipped and created traction on my shoulders. It was like someone pushing down on me for fourteen hours a day.

- How was it getting into the suit?

It’s ostensibly a wetsuit. It was like kind of a porous wetsuit. It’s basically like a rubber wetsuit that had a little bit of the fortified plastic stuff to represent the carbon armor, and then each piece of it would get clipped on.

So it was about a thirty-minute process to put it on and then about fifteen minutes to take it off.

But the real problem for the first two weeks was that everything gets done very, very quickly at the eleventh hour because the preproduction was quite short on this film, for various reasons of scheduling.

But they didn’t ever think to put in a pee-flap. So, you can imagine, when it takes forty-five minutes to get on and off on a schedule of shooting, you don’t really want to be taking it on and off all day, but it’s really hot, so you’ve got to drink a lot of water, so these are problems.

- Did anybody just take a knife?

No, I have heard that’s happened, though. The guy at Legacy that designed the suits has done suits for other people and there was another movie with an actor that shall go unnamed who cut it from top to bottom so that he didn’t have any problems.

And then, right after he’d done that, there was a sequence where it flipped in the air, and that was a problem. But after a couple weeks they gave me a pee flap, so all was good.

- How did you get this role? How did this all come about?

I had met Guillermo a couple of years ago, well, several years ago now, when he was doing Hellboy 2, and he asked me to come in and meet with him. I don’t know if you remember the movie.

There were a prince and princess that were identical twins. And he’d already cast the girl, so he was interested in me playing the guy and he just felt ultimately when we did the prosthetic test that we didn’t look similar enough. But we really liked each other and had a lot of fun during the audition process and the prosthetic test and stuff.

So, I guess he just kept an eye on me over the years and through his relationship with Ron [Perlman], he’d been watching my work on Sons of Anarchy.

And then he somehow arrived at the decision that I would be the guy he wanted to save the world in this thing for him. So he invited me up to his famous man cave, Bleak House, and we sat and chatted for a couple of hours.

There wasn’t a script or anything for me to read, and he just said, 'Hey, there’s gonna be this giant robot and they’re going to kick the ass of the monsters and you’re going to be in the brain of the robot and you save the world.

So, you want to do it?' And I said, 'Man, it sounds good to me. I’ll do anything with you.'

- And how was the working relationship with Guillermo?

Amazing. He’s just a sweetheart to work with. He’s a very, very, just kind and generous and collaborative man. I can’t speak highly enough of him. We both really enjoyed each other.

And he just offered me one of the leads in his next movie that he’s going to do, so it’s kind of developing into hopefully something that I’ve always dreamed about, which is to have a longstanding relationship with the director and work with him over and over again.

He’s certainly expressed an interest in me being in all of his English language films from now on. He said that to me at the end of the movie, 'Oh, you’re in, my friend.' And I said, 'What do you mean?' He said, 'I’m going to put you in every English language film I ever make from now on.'

- Like he does with Ron Perlman?

Like he does with Ron. And he's a very, very genuine guy and has always been true to his word, but I didn’t quite anticipate that three months later he was going to be offering me another lead role.

I thought maybe he’d have me doing craft service or something on his next movie. [Laughs]

- Can you tell us about what drew you to acting in the first place? Were you a kid who liked it?

Oh, I grew up in Newcastle-Upon-Tyne. It was a like a pillar of the Industrial Revolution, and then all of the industry kind of systematically dried up.

The coal mines closed down, the ship builders closed down, all the cotton factories got outsourced elsewhere and the bottom kind of fell out of the city. And they’re really wonderful, salt-of-the-earth-type people up there, but it’s very socially and economically depressed.

I was always like a weird, existential little kid. I feel like I’ve been on the precipice of total existential crisis since I was about five years old.

And I just remember looking around and thinking that everyone was just so engaged all day in the brutal gritty reality of survival up there. And I just thought, 'God, what is inside of these people that they wanted to do?'

And because I was kind of unhappy, I would often retreat into film. I just loved watching films and being transported into these worlds that I just like felt like I wanted to live in myself.

And at some point, those two things became connected. I felt like if I could work in film myself, not in a grand way like what we’re doing as actors is important, but for me personally, if I look back on it at the end of my life I could feel like I did something.

- How did you get started?

There was one TV show that goes on in Newcastle, called Byker Grove, and I got myself onto that when I was eighteen.

And right at the time that I got that three episodes of that show, I also got a modeling agent that approached me. I went to this clothing show with my mom and there were some modeling agents there and somebody approached me.

And I did one modeling job, for Wall’s Ice Cream, and absolutely hated it. So I said, 'Okay, modeling’s not for me.' I didn’t get Byker Grove through an acting agency, I just got it through meeting a production manager of the show.

So I said to this agency, 'Listen, I don’t want to model anymore, but if you would send me off for acting auditions, I would love it.'

I had enrolled in college to study the theory and history of film at that point. And they didn’t send me on any auditions and I kept bugging them and they had modeling jobs for me and I kept turning them down and they were really frustrated. And then they finally just sent me out on an audition and it was for Queer as Folk, and I got it.

- Which was an international breakthrough.

Yeah, and so I got my first ever audition and then probably did about four hundred after that that I didn’t get. I just think that’s somehow the way the universe works.

If you're really a pure spirit and want something badly enough, it will give you a little nudge in the right direction and then, boy, will it make you work for it after that.

- Guillermo del Toro did something in this movie he’s never done before, which was to let his actors improvise. Did he let you do that?

Yeah, he did, actually so freely that I didn’t know that that was not something that he’d done in the past. Never, really. Well, that’s amazing, because he did it completely freely on this.

- Did you keep any souvenirs from these big sets?

No. There was some talk of keeping one of the suits, but it would have just been burned immediately had they let me keep it, so I thought someone else should have it, because I was so sick of wearing that suit by the end of it.

- I know you said modeling wasn’t for you, but I have to ask a question that all women want to know. How did you get those abs?

[Laughs] Unfortunately, there’s only one answer to that, and that’s just a lot of exercise and really clean eating. Initially, the film used to open in the present time, and then it was a flashback, and then we went back to the present. And the opening of the film was me furiously working out in a kind of cathartic way to stay sane.

And Guillermo said to me right at the beginning of me signing on to do this, 'You know, frame one of the movie will be you working out. You need to show up looking like a guy that we instantly believe is capable of saving the world.' And I said, 'Oh, Christ.'

And I was shooting my TV show at the time, so I was working a lot of hours. We worked fourteen to sixteen hour days and then I would just go to the gym two hours after work every single day, six days a week.

- How did you keep up your energy? Lots of coffee?

Zero stimulants is the only way I can do it. You start having coffee or Five-Hour Energy or Red Bull, you’re so screwed. A gallon and a half of water a day and then organic fruit and vegetables is the only way you can have enough energy to do that.

And it’s so interesting, because I see people doing it all wrong with all of these stimulants all day and they drink ten cups of coffee and then ten hours into our working day they’re like, 'I’m so tired.' I have boundless energy, and I’ve just been drinking water all day.

I mean, your body is a living organism. What do you think if you put poison into it how it’s going to react?

- Can you talk about training for your fight scene with Rinko?

That was great. To go back a little bit to the history of it, I remember seeing The Scarlet Pimpernel with my mom and thinking, 'God, how does this work? Do they just find someone who can ride horses and swordfight?'

And my mom said, 'No, I think probably they find the actor that they want to hire and then teach him how to do that.' And that just blew my mind at six years old. I thought, 'That is the coolest job on the planet.' And I’ve just maintained that belief.

So, when I get to go and do these type of things, it was so cool. And seeing the way Guillermo handled those type of sequences in the past and Hellboy and stuff like that, I just thought he was really going to go for it.

To answer your question though, I just went Saturday and Sunday every day, every weekend for about eight weeks before we started shooting and actually went down and trained at Bruce Lee’s partner’s gym. He has an amazing gym in Marina del Rey, and just learned how to do all of that stuff. And it was amazing.

- With the Hand Bells?

Yeah. Rinko and I did the vast majority of that. Sometimes, when it was my coverage, I would ask to do it with her double because I was just so nervous of hurting Rinko, because we would really fight.

I mean, we were really going for it, and with those sticks, if you make a mistake, then it’s going to be bad.

And I actually did. Bless her, there was this amazing woman who was Rinko’s double, who’s actually the fastest woman in the world. She’s the world champion in seven different techniques of weapons fighting.

But she also is the fastest striker in the world, and she was on this National Geographic show called Man Versus Beast or something like that, and they tested her strike speed against a rattlesnake and she was faster than the rattlesnake, like three strikes out of three. She wasn’t fast enough for me. [Laughs]

So, she was getting married three days after leaving Toronto and we were doing this fight scene, and there’s a moment where I do a spear stick at her and she’s supposed to duck it, and after ten hours, she just didn’t duck it fast enough, and I slammed the stick right into her cheekbone. So, she then went back to L.A. and got married with a huge black eye.

- Oh, no!

Right, but I said, 'You’re a world champion in seven different fighting styles. Of course you should get married with a black eye.' She was like, 'Yeah.'

- Can you talk about working with Idris Elba?

Idris is great. As Raleigh Becket did, I found our off-screen dynamic is very similar to the on-screen dynamic.

Sometimes I would just love Idris and have so much respect and admiration for him, and then other times I just wanted to punch him in the face. [Laughs]

- What about Rinko? Did you ever want to punch her in the face?

No, not Rinko. Rinko is just the sweetest, most lovely, charming, delicate person. I thought she was absolutely fantastic. And I’ve got to say, for all of these tough guys in this film, when we were in the Conn-pod, thinking that we’re so tough and we’ve got this on lockdown, we all ended up just crumbling under the strain of doing that.

And I swear, Rinko never complained once. Guillermo talks about this a lot, but she really did. I don’t know if it was a cultural thing or what, but she just found this zen place in there, and it was harder for her than it was for anyone, but she just would not complain.

Pacific Rim is released 12th July.