Despite having seen them play the previous night, and the fact that all pertinent research was well and truly done and dusted, it was still startling to get a load of the size difference between one member of The Cave Singers and his two cohorts.

Yes, Derek Fudesco, guitarist, towers like a folk-rock Gulliver over his more elfish, Lilliputian singer Pete Quirk and drummer Marty Lund.

Any personality traits that height might dictate are, however, nonsense in this case. In conversation these three come across as more or less the same person. More mellow men you will not find, The Cave Singers are not scintillating conversationalists.

A lot of non-committal mumbling (not without its own charm) goes on, to the extent that listening back to the recording of the interview is something Jack Bauer’s team at CTU would struggle to unscramble. But as The Cave Singers’ music and performance proves, never underestimate the powers of the innocuous-looking stoner.

The Seattle band released their first album, Invitation Songs, in the UK in February. The songs offer a beautiful (and often rather savage) melancholy, from three musicians in love with simplicity. But the most arresting thing about the album, at first anyway, is a quite lovely front cover. It depicts The Cave Singers standing in a circle surrounded by wilderness, in a three-way group hug. Brotherhood, kinship and shelter seems to be the message. As well as the fact Fudesco really is a lot taller than the other two.

“It was totally choreographed,” says Fudesco, having sat down (thankfully) in a room at their label’s headquarters in South London. “We thought up the idea for a group hug when we were high as shit and sitting on the porch. We spent the whole day on this nature reserve until we found a good spot. We hugged, like, a hundred times, and it was an old long-exposure film we used so we had to hug each time for a couple of minutes.”

Hugging and getting smashed aside, Invitation Songs is an album of many moods and colours. From the hard acoustic/synth exercise of ‘Helen’ to the chilling blues of ‘New Monuments’ or the relative gentility of ‘Seeds of Night’, the album is one of those obscure gems that come from nowhere that suggests that life might be worth living after all, and that songs are still worth singing. While it is quickly clear from meeting them that they are a definite three-way creative effort, the album can’t help but proffer Quirk’s insane nasal vocals as its centrepiece. This aligns it with the Bon Iver album that was released earlier this year, For Emma, Forever Ago – another folk-inflected debut eschewing instrumental excellence or politicking in favour of intensely personal ballads and the untrammelled beauty of a lead singer’s voice.

Of course, they never set out to push Quirk’s voice to the fore. “That’s just how it happened,” says Fudesco matter-of-factly, “most of the record was written with Pete and I just writing over a guitar. It was so simple, just the two things.”

Lyrically, Invitation Songs is pretty glum. ‘New Monuments’ is about a ‘house of disrepute / Where I lost my mind’ while pervading the whole thing is a sense of wrath (and redemption, let’s be fair) from higher powers, as well as the odd love song. Quirk is typically laconic when asked about the melancholy.

“I’m sad,” he says to loud guffaws from his bandmates. “I’m really sad.

“It was the winter in Seattle and there were things going on in my life that were kind of sad.”

Reviews that met Invitation Songs were generally good, though a few, fairly reasonably, suggested the lack of instrumental oomph and sparseness pointed to either a lack of ambition, or a band still struggling to work out the sound they wish to achieve. This can be countered by the fact that each member of The Cave Singers had, Quirk says, previously been in bands that were proggy, heavy, with lots of yelling. The Cave Singers were toning themselves down to what they felt comfortable with from a louder place, rather than starting out their musical careers trying to ape Nick Drake or Gram Parsons. After his previous band had split, Quirk went back to basics.

“I started recording by myself, just in my room,” he says, “so I kind of had to keep it quiet. But I also wanted to focus on singing more and just bare accompaniment. Derek was recording in his room - we lived together - so we started swapping tracks and stuff.”

The other possible reason why the album is so austere is simply that they couldn’t afford anything else. Like so many excellent bands from the Pacific North West, the Cave Singers must work normal jobs like the rest of us. Quirk is a bike messenger, Lund a barman and Fudesco works on a market stall. “Unless you’re selling 100,000 or 200,000 records you have to work,” mourns Fudesco.

The financial problems meant that Invitation Songs had to be recorded in three separate batches… “we didn’t have enough money to record the album all in one go,” says Quirk. They recorded one of those three batches in Vancouver, where they came across soon-to-be best friends and tour-mates Black Mountain. The Canadian rock band loved the Cave Singers, and Amber Webber sings on Invitation Songs.

“Vancouver has a great scene where everyone plays together and helps each other out,” says Quirk, “and they kind of invited us into that. Once we recorded those songs with Amber she just started sending our songs to everybody and telling people about us. It was really awesome.”

With songs for a new album and second European tour in six months to enjoy, Webber’s devotion (along with blogosphere hype and in Matador, once of the heavyweight indie record labels) is well founded. The new songs are, according to Fudesco, “more complicated, the song structure is different, there are songs with more than one chord and its not quite as melancholy”, but given the formula for Invitation Songs worked so wonderfully it would be a shame to deviate too much. The classic Cave Singers sound? Quirk sums it up pretty well: “kind of reclaiming hope or something like that, self improvement.” More loud guffaws. “Maybe a little bit of spirituality, searching for that.”

The Cave Singers play Bush Hall on 26 June 2008.