Like all good things in life, the formation of the Wellington International Ukulele Orchestra was organic. ‘It happened without any of us knowing what was going on,’ says Age Pryor, who founded the orchestra back in 2005 alongside Bret ‘Flight of the Conchords’ McKenzie. From unassuming beginnings – originally a group of friends who’d meet in a local café to play together before work each morning – the group’s reputation for peddling relaxed, feelgood ukulele sounds saw them rise from these lo-fi gatherings to selling out theatres across the globe.

It’s easy to see how the no-frills, relaxed atmosphere of the WIUO has slotted nicely with the increasing popularity of this instrument in recent years. With 12 members plucking away at ukuleles and one double bass (shaped, of course, like a uke), there’s no front man, no egos, just a group of mates providing original, delightful and often mischievous musical treats. ‘Music has gone a long way from the 60s and 70s where heart and soul was absolutely dripping out of it,’ Pryor reckons, citing the 80s and 90s as being all about ‘production and jeans. The ukulele might be a way to get back this heart and soul.’

Indeed, the group’s game plan is simply to provide audiences with music they love, played by people who love it just as much. This ‘anything goes’ motto means that in a typical show, the orchestra will stroll through traditional New Zealand folk tunes, irreverent versions of pop songs and some unadulterated crowd-pleasers. Pryor admits that Toto’s ‘Africa’ is one of his favourites to perform, but stops short at considering their gigs as being in any way tarred by the novelty brush. ‘For me there’s always been two levels to the band: there’s the entertainment factor and there’s the musical content. When those two things both happen at the same time, that’s my favourite moment.’

WIUO’s live shows are suffused in improvisation and wit, but while the group does have a direct foundation in comedy – that Flight of the Conchords connection – a lot of their humour is far from pre-planned. Instead, it flows naturally from the dozen vibrant personalities interacting together on stage and from the different reactions of each brand-new audience.

‘It seems risky calling ourselves comedic because we don’t have any set jokes ready to go. But the players are so funny with each other and the way the audience gets involved ends up being funny, so it just ends up being a funny show. We don’t want to intimidate or scare our audiences at all, so our aim on stage is to be as genuine as possible and to invite audience members to participate to the degree that they wish.’

This spontaneity is tailor made for the Edinburgh Fringe aesthetic, and Pryor admits that the show’s unpretentious vibe ought to go down well. He promises ‘a good time with a few laughs and a good, heavy buzz by the end of it. That’s one thing I’m really looking forward to: seeing how the conversations go between band and audience in Edinburgh. I’m hoping we actually understand each other.’

Wellington International Ukulele Orchestra, Gilded Balloon Teviot, Bristo Square, 0131 622 6552, 3–26 Aug (not 12, 19), 6pm, £12.50–£13.50 (£11.50–£12.50). Previews 31 Jul, 2 Aug, £7.