The Boxettes, Kings Place

The band's Facebook page states “Dirty Soulful Groovin Dancey Sweet” under genre. To which I'd add “Dramatic Playful Intense Voluptuous Transporting”. Performing last night as part of the London A Cappella Festival, The Boxettes swept away any residual festive cobwebs and dazzled a packed Kings Place. “Loosen your shirt, loosen your bow ties,” we were told.

The all-female, London-based vocal quintet comprises Belle “Bellatrix” Ehresmann - currently the female world champion beatboxer - plus Alyusha Chagrin, Yvette Riby-Williams, Neo Joshua and newest recruit Kate Brown. While the band's roots lie in jazz – the group came into being in 2007 when they were studying jazz at the Guildhall School of Music and Drama - their sound has grown to embrace hip hop, soul and grime.

The group's single set pinned you back in your seat from the get-go. Featuring a combination of unison singing, blissed-out harmonies, solo vocalising and beatboxing, the quintet's use of extended vocal techniques and distinctive vocal timbres created a sound palette that ranged from the impressively vast to the engagingly intimate.

From the gorgeous harmonies of “Hattie” and sub-bass beats of “Cracks” to the soaring lead vocal of “Macy Brown” and the surprising false ending of “Puppets (on a String)”, the evident craft, passion and spirit that the band poured into their all-original material was completely heart-warming. Opening up new vistas of vocal expression, The Boxettes really have something quite unique to say. The improvised piece based on a phrase suggested by the audience – the slightly perplexing “Show us your teeth” - elicited a bravura display that was also successfully mined by Neo for its comic potential (“You've had too many sweets” she sang, ever so sweetly).

Bellatrix's solo feature midway through the set was astonishing in its super-fine rhythmic precision, contrapuntal complexity and its heart-stopping virtuosity. You could only marvel at the squelchy, subsonic lip bass, skittering rim shots (complete with cathedral-like reverb) and crazily inventive fragments of scratching and other fx, all of which somehow seemed to be in play at the same time.

Hats off, too, for The Boxettes' sound man. Given the wide range of sonic frequencies that were in play, the fact that there was never the merest hint of feedback was nothing short of miraculous. Through his creative sculpting of the sound, it was rather like having an unseen sixth member of the band.

The evening opened with a brief, four-song set by Cadenza, a Cambridge University group well known on the college circuit who were winners of the 2010 Voice Festival UK. Their a cappella arrangement of Bonnie Tyler's “Holding Out for a Hero” brought the house down. Now there's a sentence I never expected to write.

This third edition of the London A Cappella Festival ranges from cool Canadian Rat Pack Cadence and last year's Edinburgh Fringe favourites, FORK, to the stunning contemporary jazz of the London Vocal Project and the festival curators themselves, the legendary (and five-time Grammy-winning) Swingle Singers. The three-day festival also features workshops, free foyer events and a panel discussion.

• 2012 London A Cappella Festival at Kings Place
• The Boxettes on the web

Watch The Boxettes perform “Free”