Highlights & low notes: Noah and The Whale

Charlie Fink doesn't look like a pop star. Propped up against a picnic table outside his King's Cross local in central London, with a cigarette in his hand and a tired, sheepish grin on his lips, he looks more like a shy, dishevelled student than the man responsible for writing and performing one of the summer's biggest pop hits.

But that's exactly who he is; "5 Years Time" by Fink's band, Noah And The Whale, had the whole country whistling along to its irrepressible exclamations of "fun, fun, fun" and "sun, sun, sun", spending 12 weeks in the Top 40 (it peaked at No 7) and becoming the second most-played song on UK radio in August. Not too many folk artists have appeared on the all-conquering Now compilations, but you can bet that the fiddle-powered "5 Years Time" will be on the one that's out just in time for Christmas.

Today, sipping a whisky and coke, Fink is clearly still coming to terms with the unlikely success of that first single release from the band's life-affirming debut album, Peaceful, the World Lays Me Down (which itself reached No 5 on its August release). It's just been announced that they will play the 2,000-plus-capacity Shepherd's Bush Empire in March and Fink's mind appears to be boggling at the prospect. "It's all so terrifying," he says. "I can't even think about it. Playing big venues has never been an aspiration for us. Every time we go that bit further with things, I think, 'shit, I didn't mean to be here'."

Watch: '5 Years Time'

Fink has always loved music, but it never occurred to him that he would make a living from it. As a child growing up in Twickenham, his mother, a nurse and part-time folkie, flooded the family home with her records: "I remember being about five listening to Buddy Holly and The Beach Boys and feeling so excited," Fink says. "It's a feeling I don't think you get as an adult. I guess ever since then, music's been an obsession. There's really nothing cooler."

The front man's formative experiences instilled in him a love for melody bordering on addiction. From 12, Fink began tinkering with instruments, compulsively strumming on guitars and recording tunes on old cassette tapes. But he always shied away from writing his own lyrics. "I didn't feel I had enough to say," he shrugs. It wasn't until Fink was 17 that he found the inspiration to write, although the incident which prompted that doesn't sound very pleasant.

"I don't talk about it much," Fink says, cautiously, "but I had an awful experience at a festival and, to cut a long story short, I nearly died." The singer won't go into details, but the incident left him suffering panic attacks, consumed with the reality of his own mortality and convinced him that if he went to sleep he'd never wake up. Yet it was this brush with death and its philosophical fallout which finally sparked Fink's songwriting. He spent much of a miserable first (and only) year at Manchester University sitting in his bedroom, trying to explore his feelings through his writing.

For a long time, Fink's songs seem to have been something akin to a diary – a way for him to sort out the muddle in his head, but not something he really expected to share with the outside world. It was Fink's friend Laura Marling who was largely responsible for changing that, when the now critically lauded artist coaxed Fink on to the road, as her support act in 2006. "Before then, I didn't take my music at all seriously," says Fink. "I turned up for that tour with just a ukulele thinking it would be a bit of fun." It turned out to be much more exciting and satisfying than that, prompting Fink to form Noah And The Whale with fiddler Tom Hobden, bassist Matt Urby and his (Fink's) drumming brother Doug.

Watch: '2 Bodies 1 Heart'

The band began to develop its sound, gigging around London and recording low-key singles for indie label Young And Lost Club. Marling was so impressed with Fink that she recruited him to produce her debut EP and then her first album, Alas, I Cannot Swim, which went on to be shortlisted for this year's Mercury Prize. Speaking to The Independent back in January, the chanteuse, who lends her golden voice to "5 Years Time" and much of Fink's album, was gushing in her praise of the band's talent: "Theirs is the best new music I've heard in a very long time," she said, "I think they're going to change the world."

They haven't quite managed that yet, but "5 Years Time" has caused a minor global ripple. The track has been commandeered by adverts for cereal, cars and phones, as far afield as Austria and the US (where the band have just spent several weeks touring). Fink tells how one of his friends was on a much-delayed aircraft where the captain played the track to calm his angry passengers (it worked). And he glows with pride when recounting the song's appearance on Match of the Day. "I know I've been frustrating my parents for years, but when my dad heard our music on the TV, his face was a beacon of joy. It's not like you can write a song and say, 'mum, listen to this, it's all about sex and death'. So, yeah, that sort of thing is nice. But, of course, I know I mustn't get used to that kind of recognition."

That caveat isn't so much pessimism as realism. In years to come, the phrase "one-hit wonder" may well attach itself to Noah And The Whale, who never planned to hit the pop heights, and as such seem unlikely to scale them to the same degree again (though their follow-up single, "Shape of My Heart", is another catchy little belter). But, at the same time, it would be a terrible pity if Peaceful, the World Lays Me Down was entirely overshadowed by its chart smash.

Watch: 'Shape of my Heart'

Hewn with heartfelt emotion and laced with bittersweet melancholy, Fink's morbid anxieties and unrequited yearnings tumble from the record. But these dark bones are fleshed out and given life by stirring melodies. Echoes of Bonnie Prince Billy and Smog resound in the optimistic acoustic guitars that lift Fink's loneliness. Inspiring piano-led arrangements as delicate as snowflakes swirl gracefully about lyrics of loss, while elsewhere Arcade Fire-like grandeur burns brightly beneath buried hope. If "5 Years Time" showcased the band's knack for a radio-friendly tune, the album proves their depth.

Fink, though, doesn't seem overly concerned about the band's future, beyond the fact that he's itching to record the next album, which he's finished writing. That in itself proves their success hasn't gone to his head. "I definitely can't write when I'm content," explains the man behind the merriest-sounding song of the year. "If I ever did get really happy, I'd maybe have to give up."

Noah And The Whale tour the UK to November 13 ( www.noahandthewhale.com ). Single 'Shape of My Heart' is out now