They may look like S Club 7, but don't be fooled by the young, attractive line-up of four girls and three boys (including the doppelgänger of Spencer from Made in Chelsea), or their colourful dresses, dance routines and misleadingly traditional name; The Vocal Orchestra are basically the anti-Glee.
The troupe, which is the world's first beat-boxing choir, have been put together and directed by Shlomo, who is 'the Harry Potter of beat-boxing', in the immortal words of Tim Westwood. Their super-slick but joyously fun performance at the E4 Udderbelly Festival is a rollicking good ride, providing 60 minutes of full throttle entertainment.
With only each other's voices for accompaniment, the Vocal Orchestra create inhuman bass lines that made the ground shake, uncanny synthesizer sound effects and spine-tingling solos and harmonies, while forming themselves into human DJ decks, drum kits and time machines.
At the risk of pointing out the obvious, I still find it astonishing that the whole show is just formed of 7 human voices - despite there being no instruments whatsoever, their 60s pop, 80s electro and 90s dance medleys sounded uncannily like the original tracks. They even told us they'd only been performing in this line-up for 5 days before the show, which is pretty incredible given how seamlessly slick and in-sync they were; they made Diversity look like a gaggle of uncoordinated oafs.
I couldn't find a clip of the current line-up as they're so new, but here's a small taster of what you can expect from The Vocal Orchestra:
Amongst their creative set pieces this year are a slow motion 'Street Fighter' style battle to the death, and a mash-up between a classical string quartet and Salt'n'Pepa's Push It.
After all that relentless energy, what really took my breath away was their goosebump-inducing cover of Massive Attack's Teardrop - starting with the gentle pattering of the rain, the beat of the drums and the deep bass, before the chimey background music gradually comes in and then, lastly, the haunting vocals by Claudia Georgette.
It's quite surprising that talent like this isn't already world-famous - this lot could sail through The Voice, The X Factor or Britain's Got Talent and win all three if they were that way inclined - but my guess is that they aren't. We went and said hello after the show and one of the girls looked bemused when I made the Glee comparison. (Thank God I didn't mention S Club 7).
They're performing at the Udderbelly in Southbank until 27 May, and then at the Edinburgh Festival in August. Do not miss this!