IT began as a challenge between two musicians confronted with a Smurfs toy guitar and now it's an international sensation that's collaborated with David Bowie, the artist formerly known as Cat Stevens, the Kaiser Chiefs, the Ministry of Sound, and appropriately enough, Madness.

It’s starred at the Carnegie Hall (the New York one) and the Proms and even spawned a tribute band, which is not bad going for an outfit that’s been called a tribute band itself.

The Ukulele Orchestra of Great Britain (UOGB) – for it is they – have also been at the forefront of the artistic renaissance of one of the most put-upon instruments in music. Once the butt of countless jokes and associated with George Formby cleaning windows or Tiny Tim tip-toeing through the tulips, the humble ukulele is now the instrument de nos jours, fashionable, chic you might say, and in fact Chic, as the great funk hitmakers’ Le Freak has become a UOGB mainstay, its riff underpinning the band introductions.

“It’s true that when we started the ukulele was regarded as a joke,” says Richie Williams, the man responsible for the initial challenge that led to the band’s formation. “But if you go on the internet, you’ll see that there are some fantastic players out there. That guy who does Billie Jean plays the guitar, bass and drum parts all at once. Amazing. We’d like to think we’ve played our part in the resurgence of interest in the ukulele but when we started it was a bit of a novelty for us, too, to be honest.”

UOBG band lore has it that it all began in 1985 with a gig at the Empress of Russia pub in London. But the trigger for the band’s formation was when George Hinchcliffe, Williams’s fellow founder member, was round at the Williams household one day and picked up Williams’s then-young son’s Smurfs guitar as if it was some sort of archaeological exhibit. Realising it only had two strings on it, Williams said: “Go on, I dare you to try and get a tune out of it.”

Hinchcliffe, who was then plying his trade as a Hammond organist alongside Williams in the band that routinely backed up Motown stars such as Mary Wells, Martha Reeves and Edwin Starr on UK tours, instantly put Williams’s gas at a peep.

“George is a great musician, the sort of bloke who can knock a tune out of pretty much anything,” says Williams. “So of course he could play a two-string guitar. But it set me thinking. There we were lugging all that gear with the band – it’s not just the Hammond organ, the Leslie speaker cabinet that goes with it means you really have no friends at the end of the night – and I said, ‘We should put a band together that plays ukuleles. You know, there’d be no more amps. We could turn up at the gig with all we needed under our arms’. Brilliant.”

Sympathetic friends, who weren’t all instrumentalists, were rounded up, a set list was organised, the Empress of Russia’s back room was booked and it promptly sold out.

“People were intrigued and the response was pretty amazing,” says Williams. “But the great thing about the ukulele is that it’s dead simple to play. Kitty Lux, who’s still with the band, was a singer we sometimes worked with and George bought her a uke and said, ‘Here, have a go’. Almost overnight she was a ukulele player. And I think that’s been part of the instrument becoming so popular. Anyone can play the ukulele, although I play a baritone, which is tuned like the first four strings of the guitar, so I can’t really call myself a ukulele player.”

Williams can’t remember how the UOGB’s propensity for playing rock anthems such as Bowie’s Life on Mars, Pink Floyd numbers and running a general gamut from Tchaikovsky to Nirvana via Otis Redding and Spaghetti Western theme tunes began, But within three years of that first pub gig, they had released an album to some acclaim, appeared on BBC TV, played at WOMAD and recorded a BBC Radio 1 session. So they were obviously doing something right.

“I actually left the band for a while and moved up to Yorkshire, where I played mostly corporate entertainment gigs, and I missed the band’s big moment with David Bowie, although he’s obviously a fan because he put a link to us on his website,” he says.

“What happened was, there were some members who weren’t full-time musicians and couldn’t always get time off work for the foreign trips. So I got brought back to dep for these gigs and then six years ago, by which time the band was a full-time concern and I was living in Dorset, they asked me to rejoin permanently – and it’s been brilliant. I’ve gone from playing music for people to chat over to playing for people who really want to listen.”

And, he might add, play along with their favourites. Go to UOGB’s website and you’ll see proof of them having some two thousand extra band members playing along on ukuleles at the Royal Albert Hall during the Proms. There’s video proof, too, that they’ve become a stadium rock band, although Williams isn’t so sure about the auxiliary band members in the audience on that clip, which comes from their New Zealand tour – because most of them are hitting the ukuleles like tambourines instead of strumming them.

“What’s been a particular eye-opener, for me, is to have seen how well the band has travelled,” he says. “We were in Finland recently and you might think, ‘well, they’re not going to get this over there’. It’s basically a bunch of people making twits of themselves. But the Finns got it. The Swedes and the Germans definitely get it – they love us over there – and I suppose it’s that thing where some humour translates easily. Monty Python is a great example. And other humour doesn’t translate at all.”

The laughs in UOGB’s music don’t always come easy. Arranging songs can be a lengthy process and although the band’s modus operandi is generally to burst the bubble of pomposity in music that takes itself ever so seriously, there can be a genuine poignancy in certain numbers.

“What tends to happen is someone in the band will suggest a number and the rest of us will either ridicule it or say, ‘yeah, that’s a good ‘un’,” says Williams. “Sometimes, even though we’ve all liked the idea, it’s taken us ages to get to a point where we feel comfortable with something. Le Freak was a bit like that.

“It sounds groovy now but it didn’t feel natural to begin with. It’s become a centrepiece of the show but it’s been going through some changes lately, so if you come to see us now, you’ll hear some surprises – and you’ll also hear the smallest ukulele in the world on that number. I thought it was a hoax myself but this is the genuine article, from Hawaii, and it plays fine. It’s just really, really tiny. So be warned.”

The Ukulele Orchestra of Great Britain play the Queen’s Hall, Edinburgh tomorrow [Friday April 29]; Music Hall, Aberdeen, Saturday; Eden Court, Inverness, Sunday and return to Scotland to play the Theatre Royal, Glasgow on May 23.