The trick is to transform something relatively easy into something dazzling and bewilderingly complex. Seeing the Ukulele Orchestra of Great Britain is like watching eight masters of close-up magic. You’re not quite sure where to look, unable to believe quite what you’re hearing. These are boom times for the four-string ukulele. You can pick up a functional instrument for a tenner and learn three chords in five minutes, meaning that a huge repertoire of Western pop songs is yours for the taking. Simply strumming isn’t particularly difficult. But what the Ukulele Orchestra do is pluck, pick, slap, whistle, shout, hum and harmonise, and they do so effortlessly.