Alt-J: the geeks in line for the top prize

On a scale of one to 10 – 10 being excellent – this year must rate in the hundreds for Cambridge-based four-piece Alt-J.

Having released their debut album, An Awesome Wave, to a veritable standing ovation from critics and respectable commercial success, the band named after the Apple keyboard shortcut for a delta symbol has already been dubbed "the new Radiohead", and forthcoming headline tours on both sides of the Atlantic are almost sold out. Oh, and their record has just been nominated for the Barclaycard Mercury Prize, having already been odds-on favourite to win it before the nominations were even announced.

This string of achievements is made even more impressive by the fact they are mostly founded on word-of-mouth recommendations. Yet Joe Newman (vocals/guitar), Gwil Sainsbury (bass/ guitar), Thom Green (drums) and Gus Unger-Hamilton (keyboard) are the epitome of modesty when we meet on one of the sunniest days of the year.

"It's very flattering to be tipped to win [the Mercury], but I don't think we should take it too seriously," says 23-year-old Gus, the youngest of the four. "It's a dream come true for all of us to be nominated and now we're just really looking forward to the night…" he adds. "And we're particularly looking forward to [eating] the chicken in a basket," Gwil jokes.

The lads are clearly great mates, almost constantly laughing and completing each other's sentences. Having met at Leeds University around five years ago, it wasn't long before they were writing tracks in between studying for their degrees (three fine art and one English between them).

"We worked out pretty quickly that we had a kind of chemistry as friends that we could translate into our music," says frontman Joe.

But the band admits they were shy of talking about the music they made. They insist, as Gwil explains, that they still "never collectively think about bands or what we want to sound like".

"It was almost like the love that dare not speak its name," jokes Gus. "We just thought, 'Let's see if it works'. And thankfully, it did." At the cost of their university lifestyle, they spent years cultivating their sound, reaching a turning point when they wrote "Tesselate" – a passionate yet menacing song that uses a geometrical analogy for sex.

Alt-J go to great lengths to temper the praise An Awesome Wave has received. But it is an impressive, inventive record that almost feels too mature for a debut, with songs such as "Breezeblocks" exploring the textured themes of love, relationships and mortality, set to a layer cake of creeping synths, clattering beats and haunting vocals.

"The strange thing about making an album is that you can never ever hear it for the first time, and I still have loads of things I'd like to change," says Gwil. "Ultimately we are really proud of it, but we were aware that plenty of good albums still go unnoticed."

The band is beginning to come to terms with the attention they are receiving from a rapidly growing following of "actual fans", as a wide-eyed Thom describes them. "Some people made T-shirts just for the Reading [festival] show," he says. But Alt-J has also learned to take criticism. "After a gig we're straight on Twitter to look at what people are saying – unashamedly so," says Gus. Gwil agrees: "If you don't want to know what people are saying, I don't know what you're scared of."

Most negative comments accuse Alt-J of being pretentious or posh – the latter of which Thom denies outright. "Some of the greatest people in music have been pretentious, and isn't that what being in a band is all about?" says Gus. "Plus we're writing songs about what we think – that's pretty pretentious."

Joe – the driving force behind the song-writing process – comes up with the basic outline on acoustic guitar and writes the lyrics before taking it to the band. They write their parts and restructure the song together. "Then we take it to our producer [Charlie Andrew], who might say this bit isn't working…" Joe says.

"It's inevitable that you take the criticism personally…" says Gwil. "I've cried," Gus admits. Gwil agrees that he has too. "For the record – I haven't cried," Joe smiles.

The acclaim Alt-J has received, and the hype around the Mercury Prize nomination, "puts quite a lot of pressure on us", says Joe. With an expression that reflects the weight of the expectations now placed on the band, he says he believes the comparisons with Radiohead are "premature".

"Radiohead have had an amazing career and we've only just done our first album," he says, pondering the potential pitfalls of the band getting ahead of itself. "We don't ever want to find ourselves writing an album that we don't feel comfortable with. It'd be horrible to hear anyone say, 'Alt-J: First album was great, second album was really good, third album – they just blew it."

For the time being, Alt-J can be content with breaking America, even before they've finished breaking the UK and Europe. Currently touring to promote the album's US release this month, they say they're happy to "blitz" as many opportunities as they can. Even on the road, the band is focused. "We've been playing live together so much recently that I felt as though we've got a lot better as musicians," says Thom.

No wild tour stories? "We invented a pretty cool game called 'Throwy' while on tour in Spain," says Joe. The band laughs at this, the wildest story they can muster. "You play catch with a bottle that's half full of water but you have to move with the movement of the water in the bottle…"

"It's kind of like Hacky Sack meets contemporary dance… we just had too much hash," Gus laughs.

The hectic touring lifestyle has made the band lazy, says Thom. It may be hard to believe coming from former students, but Gus agrees: "You have everything done for you."

"As soon as we're done here, we're just going to stand and wait for someone to come and pick us up," says Thom. "And then it's on to the next thing."