Hidden in the leafy suburbs of west London is Metropolis Studios: a large warehouse building, with flight cases scattered outside and a hive of low-key activity inside.

At the end of a long day, bands, engineers and producers reflect on their progress in the mezzanine bar. But in a room of no particular purpose, the four members of Bastille are found, still a ball of productive energy despite the late hour. It’s tiring just listening to them.

The excitement surrounds their second album, Wild World. Sharing more with their debut Bad Blood than producer Mark Crew, their forte of lean sounds, bold hooks, and a dark touch has been developed.

"I hope it sounds like us experimenting," says lead singer Dan Smith. "We wanted to make a big, mad, weird, alternative pop album that takes you on to a weird journey through lots of routes and genres. Creatively, we wanted to scratch the itches of the different things we wanted to do, be it influenced by Raekwon or The Exorcist or Othello or Capote's In Cold Blood, or old films from the 1980s, or old documentaries."

Politics plays a part, too. You don't have to be Sherlock to figure out the inspirations in The Currents, with the refrain: "Still living in the currents you create/Still sinking in the pool of your mistakes/I wish you'd stop firing out the crazies". "We seem to have carved a niche of making quite hopeful-sounding songs that, lyrically, are quite questioning and potentially quite dark," Smith says. "If the first album was us growing up, this one is us figuring out what the f**k's going on."

Their reception follows a similar incline – while the first cycle saw them deliver chant-inducing songs such as Pompeii and Things We Lost In The Fire to theatre-sized shows, they're now firmly in arena territory, as proven by their 24-date tour across Europe.

Sweaty show

“It’s terrifying,” says Smith. “But it’s made us more conscious of making our production interesting. Last year, we had this falling man, and this year it’s going a step further and we have two wire mesh people to reflect our album cover. It’s nice to have visuals, to offset four guys playing songs.”

"We've yet to talk about it fully," chips in drummer Chris Wood. "So, I'm just throwing it out there: a spinning, flaming drum riser. It can happen."

It’s neat timing that almost four years to the day of their scheduled 3Arena show, they played their first Dublin headliner at the Academy 2.

At that point, they had just three singles to their name, and had yet to notch up four million album and 11 million single sales. “It was a mental, sweaty show, where the stage was half a foot off the ground and everyone was on the stage,” Smith recalls.

“When we got to go back to Ireland, we played the main room upstairs, and our minds were blown we were doing that. And then we played the Olympia Theatre. Even in London, it was the Barfly and Scala, then Koko, where there were touts outside.

“We were like ‘oh my god, this is an actual thing’. Then it was Shepherd’s Bush Empire, then Brixton Academy, then f**king Ally Pally [Alexandra Palace]. And, weirdly, now it’s the O2.

“At no point did it feel like we unfairly jumped ahead. We went up through the ranks and we’re still pleasantly surprised with where we are.”

The band are pragmatic about their work. “We’ve always been pretty honest with what we do,” says Will Farquarson. “Even with our public image, we don’t want to be the guys that slag off other bands.”

They are also quite open to corporate collaborations, from branded shows to public events such as a Mercedes Benz Evolution Tour of the US.

“Especially in the hip-hop world, the relationship with business is perceived in a different way than in the alternative world,” says Smith. “I guess now, brands are the benefactors that record companies used to be. But it has to be a careful partnership. There are really tasteless examples where artists throw in headphones in their videos and it’s really clunkily presented. And then there’s brilliant examples where it’s facilitated the most amazing music videos or a really cool show. OK Go are an amazing example of that.”

“We’ve partnered up when it was the only way we could play places, like Mexico,” says Farquarson. “Same with the Mercedes shows – we got to play free shows to our fans in the US, and while that wasn’t quite what we expected, I don’t think we’d ever do something shamelessly for money.”

For Bastille, Pompeii delivered an easy breakthrough in the US. With the radio and internet doing the work for them, the Londoners had only played a few showcase gigs before the single peaked at number 5 in the Billboard charts.

“What’s interesting about America is it’s really defined by genre, so we immediately slotted in as an alternative band,” Smith says. They have these radio station-backed festivals, so half our sets would be these massive outdoor shows, alongside people like Foals and Alt-J, but also Foo Fighters and Kings of Leon and Arctic Monkeys.”

Patronised

“But no one can really know if it’s going to take off,” says Farquarson. “It’s the thing of being in the right place at the right time. And, after the fact, a lot of people, particularly in record companies, try to figure it all out. There is an element of something happened that meant we connected…”

“And f**k knows what it was,” picks up Smith. “On paper, we make big, weird pop songs, we make mad videos that our label tear their hair out about, and we weren’t warmly received by conventional media.

“But we’ve always not patronised our fans and tried to be as creative as possible. And that’s worked so far.”

Wild World

is released on September 9th. Bastille play SSE, Belfast on November 9th

and 3 Arena, Dublin on November 10th