It was strange to see the Royal Albert Hall stage stripped of instruments, music stands or any of the usual clutter that makes up your average Prom.
With seven stools positioned artfully in a semi circle, it looked more like the setting for a Westlife tribute act.
This wasn’t your average Prom, though. Naturally 7 are a beatboxing, R&B-influenced septet of New Yorkers with their roots in gospel. There have no instruments because their voices are their tools, summoning up electric guitars, drums, cellos, trumpets and the harmonica with an extraordinary amount of discipline and vocal dexterity. It’s what they describe as “vocal play”. They have been a YouTube smash, playfully serenading a group of nonplussed Parisians on the Metro with their version on Phil Collins’s In the Air Tonight. But would they manage to charm a Proms audience?
Certainly it didn’t take long for a sea of arms to wave in time to their cover of the Isley Brothers’ Summer Breeze, but the atmosphere changed during a dramatic version of Joshua Fit the Battle of Jericho. Building up to a febrile climax, first baritone and musical director Roger Thomas prowled slowly into the audience. He was charismatic, like a coiled spring, with a sense that he could turn on a pin.
Other highlights included a Herbie Hancock medley and a cover of Coldplay’s Fix You with several of the group’s members affecting a haunting organ sound. Their harmonies were transfixing, taking Chris Martin’s rather turgid number to a new, elegiac level.
There is no doubt that Naturally 7 have talent to burn. They are a brilliant harmonic group and have the ability to open up very ordinary numbers (While My Guitar Gently Weeps) and transform them into something more complex. But there were issues. There was so much reverb, particularly on the guitar vocals, that you could hardly have called them “Naturally” 7.
The bass was so deep that it got lost amid the more delicate sounds and Thomas rather overdid his harmony on An Englishman in New York, a homage to his English roots.
If you closed your eyes, Naturally 7 did sometimes sound like an instrumental group - evident in their thumping take on Cream’s Sunshine of Your Love. But more often, they just sounded like an a capella group, harnessing the emotional power of the human voice to create a wonderful, rather haunting experience.
Hear this Prom on the BBC iPlayer until Monday 5 August: bbc.co.uk/proms