''It's a small guitar," says George Hinchcliffe when I ask him what a ukulele is. "There are enthusiasts who will bristle at my saying that, but that's what it is. A small guitar with four strings." And is it easier to play? "No," he insists. We agree that it is a bit like speaking Indonesian: easy to sound decent, but extremely hard to sound exquisite.
The Ukulele Orchestra of Great Britain, however, has clearly mastered the art. In the past year, it has played to packed houses at the Savoy Theatre and to 8,000 people at Glastonbury. When it did a gig in Japan, barricades had to be put up to guard members against being mobbed. On the orchestra's website, girls promise the players their knickers. And one fan said she hadn't seen her husband enjoy himself so much for years."That's a bit worrying, isn't it?" asks Hinchcliffe, leader of this worldwide phenomenon. But it's true that there is something exhilarating about their gigs. You come out grinning and wanting to share the experience with everyone you meet. So what's their secret? Is it sex appeal? Hinchcliffe laughs. "Well, each of the seven band members does have his or her own following. But I think it's more to do with what we represent. I think people see a good social model in us. We're a big family who work well together and help each other. We're like a political concept put into action."
But that's not how it all started. It began when Hinchcliffe decided he wanted to experience life in South America before embarking on a teaching career. He never made it past London. Instead he bought his friend Kitty a ukulele, a group of them started jamming, and in 1985 they played their first gig at the Roebuck pub in Southwark. It was packed, and radio and television appearances soon followed.
When I first saw them step on stage, in smart black tie, I imagined they were ex-City slaves who had turned their backs on capitalism for the love of a good sing-song. Alas, no. Hinchcliffe insists that there is too much emphasis today on the distinction between art and business. "We are a tinpot outfit really. But we are also a very successful business. We are serious about the music, but we don't take ourselves too seriously." In Britain, George Formby is really our only strumming benchmark. Few know that Pink Floyd's Syd Barrett started out playing a ukulele. Yet this orchestra believes that all genres of music can be reinterpreted on the instrument. Their comical versions of jazz, rock and rap classics, from "Smells Like Teen Spirit" to "Je t'aime . . . moi non plus", are delivered deadpan, interspersed with witty banter - "which is not scripted", Hinchcliffe hastens to add.
Given the orchestra's sex-symbol status, the members have remained surprisingly free from controversy. There was talk that Kate Bush had objected to their popular version of "Wuthering Heights", but Hinchcliffe claims it was just a "mix-up with the PR people", though he admits some people can be protective of their songs. Rod Argent of the Zombies, for example, was once distinctly miffed that the Ukuleles finished a set with "God Gave Rock'n'Roll to You". But hey, as Hinchcliffe points out:"If God has a string instrument, I'm sure it's a ukulele."
Despite fame, the band still plays more intimate venues. In one such place, I felt as if I was at one of my friend's parents' mid-1980s parties - all long hair and foot stamping. I was soon joining in, though, alongside a woman whose jigging nearly sent her claret over her twinset and pearls, while teenagers shouted, "Pure class!"
When I mentioned the band to an editor of a techno music magazine, he retorted sarcastically: "Just what Britain's always needed." But he should take off his headphones and listen to the fans' demands: "Pickle these national treasures for the common good!" "Make them available on the NHS!" With the ability to inspire such devotion, the Ukuleles will go far.
See www.ukuleleorchestra.com  for tickets and details