Leddra Chapman/Hamel, Jazz Café, London

Sugary show needs more bite

Leddra Chapman is the owner of a beautiful voice. It has a clear, pure tone, capable of delivering both dusky softness and considerable power. Performing live, she is every bit as assured as on record (her first album, Telling Tales, is out now), delivering pitch-perfect acoustic pop with strong backing from a band of double bass, guitar, drums and violin.

But the slickness feels a shame sometimes: a few rough edges would liven up her set considerably. It's at its best during a winsome waltz (new single Story), which has the quirkiness of Kate Nash without the irritation, and in her cover of Jamie T's Sheila. On the latter, Chapman's voice is still gorgeous, but instead of sailing along as she does on most of her songs, she skitters and pops, while her acoustic guitar playing is lively and jagged. The whole thing is more expressive, more interesting, and – bizarrely given it's a cover – somehow more personal than her self-penned romantic ballads.

Chapman is young – she and her band, who are clearly a talented bunch, all attend music college together – and her lyrics feel unsteady as yet. She too-readily falls back on love-song cliché ("I can't keep saving you"; "I wish you weren't so far away"), and says she takes inspiration from her friend's gap-year travels (in Picking Oranges) and, of all things, the film Factory Girl. If she could find a way to communicate her own experiences, instead of vague romantic yearnings, she could be on to something special. She's got the voice and the catchy, radio-friendly melodies – it would just be nice to hear a bit more of who Leddra Chapman is.

She is clearly very sweet though, all pretty smiles and gushing appreciation of crowd and venue, hands clasped to her heart. And although all this rings adorably true, there are times when it can just be a little too sugary.

The gig is part of the HMV's Next Big Thing series, and Chapman certainly looks the part: in her huge-shouldered, brightly coloured dress, tumbling blonde locks and glittery eye-shadow, she is an illustration of cute-yet-cool 2010 girl.

In contrast, the next band, Hamel, seem firmly stuck in the past. The Dutch six-piece, fronted by dandyish Wouter Hamel, play smooth lounge jazz, with shuffling drums and crooning vocals. It's accomplished enough – the band is tight, there are some strong solos on electric guitar and piano, and Hamel has a purring, slick delivery. But I was left wondering what on earth the point was; the expected modern twist or knowing subversion of genre just never arrived. My companion quipped that it was like watching an X Factor runner-up cashing in with a stint on a cruise ship. That's a little harsh – there were enjoyable moments, such as the close harmonies on March April May, and several tracks were enjoyably hip-swingable. But it feels less the "next big thing" and more the next Jamie Cullum.