For a change, the late 1960s yielded up a supergroup that lived up to its hype and then some. Ginger Baker's Air Force was recorded live at Royal Albert Hall in January of 1970 - in fact, this may be the best-sounding live album ever to come out of that notoriously difficult venue - at a show that must have been a wonder to watch, as the ten-piece band blazed away in sheets of sound, projected delicate flute parts behind multi-layered African percussion, or built their songs up Bolero-like, out of rhythms from a single instrument into huge jazz-cum-R&B crescendos. Considering that this was only their second gig, the group sounds astonishingly tight, which greatly reduces the level of self-indulgence that one would expect to find on an album where five of the seven tracks run in excess of ten minutes…