Seven people, seven microphones and no instruments… Yet there are moments of The Vocal Orchestra’s performance where you could think you were sat in the middle of a club with a pumping bass line and killer vocals. What you realise, however, is that you’re near the Thames sat in a giant upside down purple cow called The Udderbelly and, for one whole hour, every noise, every sound, every salute to some of the biggest names in music, comes from seven preppy performers who take different roles to create a thick lush sound of harmonious bliss.

Billy Boothroyd and Robin Bailey display fine melodic talent as the tenors in the group. Johanna Jolson, Claudia Georgette and Harriet Syndercombe Court take the higher registers, and Ross Green delivers some incredible bass tones – the kind that shake through your body and you become adamant that it can’t be a human voice. Grace Savage is a wonder to watch, taking on the beats. This young performer is presented as a human drum kit, keeping the group together as they sing various tunes.

But, really, how interesting can a beat-boxing show be? Directed by Shlomo, the Guinness World Record holder and World Loopstation Champion, you have to hear this spectacle for yourself. What is clearly evident about this performance is how well this septet work together and you cannot underestimate the amount of rehearsal that must have taken place in order to reach this standard. All seven are completely dependent on each other to deliver the vocals that make the audience gasp, or indeed whoop with delight as they pull off renditions of ‘Daydream’, ‘Sweet Dreams’ and a stunning performance of ‘Hallelujah’. If one performer is pitchy it’s going to affect six other complex vocal lines.

The show is also a great deal of fun. It’s not your average orchestra or indeed choir; the seven parade around the stage with slick routines, humorous parodies and take the audience along with them as they go from song to song. Don’t be fooled into thinking this is an episode of Glee – that couldn’t be more insulting to a company which eats Auto Tune for breakfast… you really need to hear to believe.

The production is great value and has great branding, and the group is certainly worth the feeling you get as you leave. The buzz was quite enjoyable. They could quite easily wipe the floor if they were to go on Britain’s Got Talent and send dear Simon Cowell’s eyes into a blur of pound signs… But I think, particularly after their headlining act at Udderbelly, that this Vocal Orchestra will go on to greater and bigger things.

It has to be heard to be believed… GO!

Vocal Orchestra is playing at the E4 Udderbelly at the Southbank Centre until 27 May. For more information and to book tickets, see the Southbank Centre website.