It would be tempting to describe the singing of Lianne La Havas at “pitch-perfect”, so beautiful and seemingly pre-ordained is the sound that emerges from her mouth. Yet that description does scant justice to the Londoner’s talent, or to our experience of listening to her, in concert, or on her remarkable debut album, Is Your Love Big Enough? Her vocals sound like Lianne has little choice in the matter: she has to sing, there’s no choice involved. Okay, yes, the way she phrases a melody, the emotion she brings to her lyrics, is so precise, and so precisely right, that you can find yourself reaching for superlatives grouped under the letter P. But there still seems something too bloodless and clinical about those words: as a singer, as a musician, Lianne is simply too untamed, too primal, to be wrapped up like a parcel and labelled with such lazy ease.

It wasn’t always that way. As a child, Lianne sang in private, to herself, as if her voice was a language she wasn’t ready to use with anyone else. “I look back,” she says now, “and it seems weird that I wasn’t more song-and-dancey about it. You know, ‘Look at me – I can SING!’. But it was just this ‘thing’ that I did – this deeply personal thing, and I felt incredibly shy about sharing it.”

Nobody who saw Lianne’s performance on Later ... last year could possibly call it shy. On the contrary: something, at that moment, seemed to crystallise, as a new star announced herself to the world.  There was an assuredness to her appearance – yet, as before, that seems too cold a way of describing it. Rather, Lianne’s poise was so notable because it contrasted so totally, so compellingly, with her music. Watching her felt like seeing a person at war – with herself. But then, that’s exactly why her songs can seem both so raw and so (ominously) calm: the emotion can be either on the surface or lurking just beneath it, but that emotion is always incandescent. With rage, sometimes, with lust, or longing, or rapture, at others. And always, always, with passion.

Ask Lianne if she’s managing to make sense of the last year of her life, if she’s keeping pace with the attention, with the manic schedules, and she laughs. “I’m still having to remind myself: ‘Yes, this is me’. I’m constantly surprised, by absolutely all of it. I still can’t believe this is my job: to write songs, and to sing them.”

Not, of course, that she views it as a job. For Lianne, it’s a mission: to pin down her feelings, and to represent them. “My whole thing, since I was a teenager, was a feeling that I didn’t really know myself. And I wanted to – I wanted to have a really clear idea of that. I found it through songwriting, through having space, through being alone. It was writing that gave me this connection to myself again. And I do think that, if all this had happened any earlier, I would have felt out of place, confused, and that would probably have come across on stage, on record.” The opening lines to the album’s title track – a song whose strung-out beginning gives no indication whatsoever of its urgent and tumultous finale – spell out that process of discovery loud and clear. “Found myself in a second,” Lianne sings, “Found myself in a second-hand guitar. Never thought it would happen ...”

But it did happen. There have been some key interventions along the way. Lianne’s Greek father, a multi-instrumentalist and avid musician in his spare time, bought his daughter a guitar on eBay when she was 18, and schooled her in the basics. Her friends, the singers Paloma Faith – with whom Lianne toured as a backing vocalist , showed her a life she hadn’t really believed in before: immersed in creativity, living and breathing music, expressing yourself in song. And Matt Hales, of the band Aqualung, was the writer and producer she turned to for lessons in craft and patience. Flying out to stay with him and his family in Los Angeles, Lianne learnt that it pays to take time – time to fine-tune, to rethink, to stumble, by chance, on the perfect song, to let that song breathe and, in the process, bring out the tiny but telling sonic detail that, combined with Lianne’s voice, allows the song to soar.

Is Your Love Big Enough? acts almost like a map of the route Lianne has taken through life, through love, in the past three years. So the kiss-off anger behind Forget, in which Lianne responds to a feckless ex’s peace offering of a song he has written in her honour, is one staging post; Lost & Found, a song positively drunk on love, is another. Everything Everything is intoxicated by rapture, Matt’s wide-open spaces allowing Lianne to lock down perhaps her most electrifying vocal to date. And Age, which finds Lianne, in a way that is at once gentle and barbed, mocking the more advanced years of her boyfriend, is yet another. “That’s a good example of the benefits of extra time,” she says of the last song. “We did a new vocal, and I think it sounds much freer – and I wanted people to hear the fun in it. We actually recorded it with my boyfriend in the room. Every time I looked at him I just started giggling.”

Listen to Is Your Love Big Enough?, and you will be reminded of other artists whose debut releases had an unforgettably arresting effect when you first heard them: it is no coincidence that Lauryn Hill and Erykah Badu were among Lianne’s greatest musical heroes as a teenager. And it is no exaggeration to say that Is Your Love Big Enough? is an album signalling similar intent. Listen, in particular, to that title track again. To the extraordinary vocal, part shimmering sigh, part pent-up longing, exploding into life. To Lianne’s extraordinary, old-school vibrato, as she finally loses patience with pussy-footing around, and lets rip at the song’s close. Okay, I’m reaching for those lazy superlatives again. Better to hand over to Lianne herself. “Is your love big enough?” is a question that mixes challenge, defiance, impatience, determination, pride and, above all, passion. It demands an answer. Who, given all that, would dare to say no?