Of all the mental images you carry away with you after seeing Laura Marling perform live, the most telling are these: of an audience leaning in as one, heads tilted, ears cocked, hanging not just on each note and word, but on every nuance; and of a singer so shy, so fixed in the moment, that her eyes are cast down, wearing a look of awkwardness last seen when Ted squirmed beneath Lord Ralph’s fumbling forays in The Fast Show. So, not a natural performer, you would think. Except that, of all the artists I saw at the South by Southwest festival in Texas earlier this month, Marling was far and away the most powerful. People floated out of her shows with expressions of rapture on their faces.

We live in instant times and expect instant results – a time when Delia Smith salivates over quick-to-cook frozen mash; when the unknown Leon Jackson spouts ready tears on The X Factor and, now apparently “known”, goes straight in at No 1 in the singles chart. Our willingness to be baffled by, to explore and work hard at understanding an art form seems to be dying. Duffy’s album, Rockferry, is No 1; Laura Marling’s debut, Alas, I Cannot Swim, is not. Only one of these is a great record. Ready answers – the instant cash prizes of forensic lyric-sifting – are not, however, Alas, I Cannot Swim’s thing. Nor do they exactly flow from the mouth of its writer in conversation.

Sitting in the shade on a 90-degree Texan day, shortly after holding another crowd spellbound with her pinpoint modern folk songs, Marling parries and mumbles, her few attempts at candid, incautious explanation preceded by a strange, shy gurgle or a wry private laugh, after which the drawbridge is again raised. The acclaim that greeted the release of her album, just days after the Berkshire-born singer’s 18th birthday in February, was dominated by a single phrase, or variants of it: the achievement was extraordinary, fans enthused, in “one so young”. Never mind that Paul Weller wrote All Mod Cons when he was just 20, or that Kate Bush came up with most of The Kick Inside as a teenager.

Certainly, Marling’s air of seriousness sets her apart – but more from other musicians than from teenagers. Some have detected in her a slightly standoffish demean-our, a complaint often made about artists who are unwilling to splurge and prefer instead to put their music out there and leave it at that. Others have described her album – which addresses scarcely well-visited pop subjects such as depression, death, religion, infidelity, selfishness and solitude – as bleak. Yet Alas, I Cannot Swim strikes me as redemptive, in that, by confronting these issues, Marling sounds empowered, not brought low. She has the confidence to realise she hasn’t worked it all out, a quality that perhaps doesmake her unusual for her age.

Ask her what she makes of descriptions such as “bleak” and “standoffish” and, after a strangled laugh, Marling says: “I wouldn’t be upset by that. Because I think, ‘Who cares? Who cares about that?’ I think having a persona as an artist is important. But you shouldn’t try to mask yourself too much, because you shouldn’t care about it too much.” She pauses, which she does a lot, often for long enough to make you conclude she has stopped talking. “On the same level, you can’t give away too much. You’ve just got to be honest. That’s all you can do; because, if you’re not, people have a reason to pick up on, you know, bad stuff.” I thinkwhat she means by this is our habit of projecting meanings onto the less forthcoming type of performer. “I’m quite tough when I need to be,” she continues. “If you’re not going to be tough, then you’re going to feel, ‘What am I doing?’ So, yes, a bit of the cold shoulder, and politeness, and all will be fine.” She laughs quietly to herself.

Later, she owns up to occasional fretting about how her album is perceived: “I have worries about what people will think of it. The obvious ones are ‘Laura Marling sells out’ [after some agonising, she signed to a major label last year] and ‘Laura Marling sounds like Kate Nash’ [she doesn’t, at all]. When I think about music, it’s about community and communication. If you’re not touching a point in someone that affects them, then I kind of think that, for my type of music, it’s pointless. I don’t write songs to try to touch people, but, because they are honest, I expect them to. If somebody said, ‘This album has absolutely no effect on me’, that would be...” – longpause – “bad.”

In any number of other artists, such bashfulness would make me want to take a blowtorch to their CD. Marling’s shyness, though, comes across not as attention-seeking, but as the outer skin of an inner being far too busy to have time for niceties or to work out a way of explaining what’s going on. During a discussion about how being articulate can lead to people assuming you’re equipped with confidence and clarity, the singer says: “People who are good with words are forever searching for the right way to express themselves, and that’s why they have no clarity.” It’s one of the best explanations I’ve heard of why so many writers are messed up behind their immaculate verbal facades/smokescreens. Marling’s facade, however, is far from immaculate. And so we turn to the songs. Which is how, of course, she would prefer it.

Alas, I Cannot Swim was recorded with a raggle-taggle of musicians she met when she moved to London, having left school at 16. These include Charlie Fink, whose band, Noah and the Whale, Marling was until recently a member of. Fink was also the producer, and the real guile of the album is that, by ornamenting the words and melodies so economically and subtly, it attunes your ear to listening in the same way. Songs such as Old Stone, Your Only Doll and Night Terror ensnare you before Marling has crept up to the microphone and sung, in her curiously noncommittal voice, lyrics whose startling imagery and honesty pin you to your seat. Weaving around these are piano, guitar, accordion, french horn, trumpet, brushed percussion and violin.

The last is played by the self-styled Tom Fiddle, of whom Marling says: “There’s something about him that makes everyone smile, I think. He’s the shyest person, but when he plays, he’s set free. He’s incredibly passionate.” Is there something unintentionally (self-)revealing about that remark?

I ask her if she is able to turn her head off, as it were. She is aware, she says, of the old writers’ trap of diarising your problems away and believing you have then dealt with them. It’s not one she intends to fall into. The strangest answer she gives comes when I inquire if she is good at detaching herself from that endless cycle of self-exploration. “I guess so,” she says, “given that I can do what I do. I guess I must be.” Though I sort of know what she means, it’s an answer that’s still resonating.

“My manic and I,” Marling sings on the song of the same name, “have no plans to move on/But birds are singing to calm us down.” This sense of restlessness, torment and constant questing thrums throughout the album. The words “belief” and “believe” keep cropping up. “I don’t have a religious family,” she says, when I ask about this (she is the youngest of three daughters), “but I’m quite susceptible to religion. I went to church by myself until I was 12, then I was a Buddhist for four years. And, for some reason, I’ve got three people in my touring band who are religious. I get panic attacks before gigs sometimes, and they’ll come and sit next to me, put their arms around me and say a prayer.”

On cue, the birds in the tree above us burst into song. Beneath them, Laura Marling looks very calm indeed.

Alas, I Cannot Swim is out now on Virgin

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