Did Wolfmother spring from outer space, or drift down to Earth from the tail of a comet? Did they slip into our age from another dimension, burrowing through a wormhole in the space-time continuum to land in Sydney, Australia in the 21st century? Where did they come from? Never, except for tribute bands, have I witnessed a group performing in one era whose music owes so much to another. These hairy Australian rockers are steeped in the lore of late-Sixties psychedelia and early-Seventies hard rock, their singer Andrew Stockdale shrieks like Ozzy Osbourne, Ian Gillan and the rest of the rock-wailers, and their songs are masterpieces of riffery, with all manner of proggy noodling and tricky time signatures and changes of pace.