By summer 1973, less than a year after the conclusion of their Space Ritual extravaganza, Hawkwind had completely revamped their stage show and live set, dismissing several old favorites and standbys in favor of a whole new crop of numbers -- including a few that would never make it onto a studio album, and several more that wouldn't even get into the studio.

It is those tracks that, initially, seem the most interesting aspects of this defiantly lo-fi recording, taken from Hawkwind's appearance at London's Wembley Arena that July.

But before an imaginatively titled album is completely written off as a sonic wasteground (as all too many critics seem prone to do), it is worth considering that the versions of "Master of the Universe," "Orgone Accumulator," and "Silver Machine" included here are at least the sonic equal of their more brightly heeled cousins.

Still, the real treats lie among the new pieces.

The opening "Gaga," the first of the "lost" Hawkwind numbers, is little more than a couple of minutes of atmosphere and chatter.

But Nik Turner's sci-fi nightmare poem "In the Egg" could readily have replaced "Sonic Attack" (also present here) among the band's most chilling pronouncements, while it is impossible to remain unaffected by the coupling of "Wage War" -- a Burroughs-ian rampage through a future uprising -- and "Urban Guerilla," the band's then-newly released (and banned) single.

The imagery is as astounding as it is violent, a blow-by-blow recipe for the overthrow of civilization that is just as terrifying today as it was feasible at the time.

Indeed, champions of the underground that they were, Hawkwind might not have been speaking from experience, but they were certainly preaching wishful thinking.

Again, Bring Me the Head of Yuri Gagarin is a difficult listen, a muddy stew, a distorted rattle at the back of your ears.

But it is also the sound of Hawkwind at their absolute peak, at a time when the revolution was still a romance waiting for consummation.