Seeing a tribute band can be a strange experience. There are your heroes on stage once more, magically rejuvenated and playing the music of your youth. You too feel briefly young again – until you notice everyone else at the gig is also at least 57. But as often as not the band is brilliant. They have lovingly tracked down the right guitars, effect pedals and amp settings in search of the perfect sound. They have styled their hair just so, applied the requisite tattoos and, at some obvious expense, commissioned perfect replicas of signature stage outfits. See Björn Again and the girls might come complete with the purple capes worn for Abba’s 1980 world tour before changing into the white-booted ‘SOS’ look.