Read Neil McCormick's interview with the band's frontman Dan Smith about how he got over stage fright to become one of British music's biggest success stories of recent times ...
Bastille was the British debut success of last year. Their single Pompeii sold two million copies around the world.
Their album, Bad Blood, went straight to number one in Britain spending six months in the top 10 before becoming the highest entry by any new British artist in America (at number 11) in 2013.
Yet no one saw this coming - not critics, not their record company, not even the band.
"Led by me, we've always been a group of pessimists," says Dan Smith, singer, songwriter, keyboard player and producer for the London four-piece.
"Our expectations have been incredibly low. I never, ever imagined leaving Great Britain. For us, going to Scotland was a big deal."
As the popularity of traditional bands waned, the record industry openly fretted over whether there would ever be another Coldplay again. And then Pompeii lifted Bastille to the head of the pack.
"We've been pleasantly surprised," says the understated Smith.
If you are still trying to place them, Pompeii is the song that starts "eh-eh-oh, eh-oh", like a choir of autotuned monks chanting over a burbling synth.
Although the Roman town was never mentioned in the song, the 27-year-old explains that he was imagining what the dead victims might have to say to one another.
"If you close your eyes, does it almost feel like nothing's changed at all?" Smith sings in a soft, clear, tuneful voice."Oh how am I going to be an optimist about this?"
"It is essentially about fear of stasis and boredom," explains Smith. "Being quite a shy, self-conscious person, I was afraid my life might get stuck."
In a rehearsal room in south London, Smith is polite and eager to help. Bassist Will Farquarson joins the interview, while drummer Chris Wood and keyboard player Kyle Simmons mess about with samples. Smith is generous in deferring to his band mates but, in a sense, Bastille are barely a band at all.
In their earliest days, they were Smith's backing group, although the singer himself was so nervous on stage he made Farquarson stand at the front playing bass and singing backing vocals, while Smith "sat cowering in the back in the shadows, fiddling with loop pedals, staring at my fingers and singing to the wall.
Then at the end of the gig, I'd mumble, 'We've been Dan Smith.'?"
"People were quite confused," notes Farquarson.
Becoming a band has, Smith explains, given him confidence and helped share the load. There is evident camaraderie between them. The band name refers to Smith's birthday, which falls on July 14.
The music they make, with its synthetic colourings, is close to mainstream pop, but with a strand of seriousness and grandeur that you find in epic keyboard-led rock from Genesis to Coldplay.
Smith writes and demos everything himself, and suggests that, for the modern musician, "production is an instrument. We are a generation who have laptops with Garageband [the Apple recording app] on them and you can bring in instruments that we never saw in a cupboard at school, where you'd be lucky to find a recorder.
"And you can mess around and distort them and do whatever you want. There's no guitars on the album at all and it became a fun challenge to make music that sounds like indie rock without ever having to resort to hitting the fuzz pedal to bring the chorus in.
"Instead, we use things like layered vocals, string arrangements, interesting beats and electronic sounds to achieve the same effect in surprising ways. To me, the songs are the most important thing, and if you've got good songs it doesn't matter how you dress them up."
Smith strikes me as one of those intense, insular songwriters for whom music has been a kind of secret lifeline.
He started writing songs aged 15 but says he was so private about it that "the only way you would ever know is if you walked past my bedroom door and heard me harmonising with myself".
He had become fascinated by "a lot of the music my parents listened to - the Beach Boys, the Beatles, Crosby Stills Nash and Young and Simon and Garfunkel. I was obsessed with harmonies and how to put songs together in lush soundscapes. But I don't know what it was all about really. Kids have a lot of time on their hands."
He studied English at Leeds, where he befriended a band, Kid iD (who evolved into highly regarded rock group To Kill a King). They were the first to hear his songs ("by accident", says Smith) and encourage him to pursue music.
Another friend entered him into a local competition, Bright Young Things, which he won. The prize included a gig, which he performed solo.
"I found being onstage traumatic. I was a wreck." And yet the experience revealed something to him. "I realised if some part of me didn't really want to do music for life, I wouldn't put myself through that." Having secured a place on a journalism course, he deferred to put a band together.
Bastille's progress has been surprisingly smooth. Audiences sought them out despite the band barely making a ripple in the mainstream media. "We've been quite generous with our music. We released singles on indie labels, made videos with friends, gave away mix-tapes [free albums of Bastille performing covers]. It's been a labour of love."
Gigging relentlessly, they quickly realised people who had heard their music online were seeking them out.
They signed to Virgin at the end of 2011 which gave them the resources and clout of a major label but, says Smith, they have continued to operate in the same cottage-industry fashion.
"I run our Twitter and Facebook pages, because I feel it's important to maintain a personal relationship with fans."
Every band is trying to tap into the same online zeitgeist. In the end, what raises Bastille above their rivals are Smith's perfectly formed songs - gems of articulated insecurity, sensitive and melodic.
They are not remotely hip, but neither were Keane or Coldplay. They are a people's band. Smith talks with surprise of fans telling him he has "articulated exactly what I think and how I feel". To him, "that's mind-blowing. I've never really thought about the songs going out into the world before."
As busy as success has made them, Smith says that "after everyone's gone to bed, I still find myself sitting at the computer writing songs. It's a nice reminder that this has always been a kind of hobby that I get on with because I really love it."