Warthur The Rolling Stones were playing Hyde Park in July 1969 and wanted to get a good set of support bands together and make a proper mini-festival out of it; word of mouth had reached them that this King Crimson lot who hadn't even put out an album yet were pretty good, and so Robert Fripp, Greg Lake, Ian McDonald, and Michael Giles stepped onto the stage and into the limelight - and that momentous event in the band's history is captured here.

The sound quality is, on an objective basis, only fair - but for a tape of a live band on a makeshift stage in an outdoor festival from 1969, it's pretty good, and provides more or less the earliest glimpse we have of their primal stages. Though much material will be familiar from the debut album (and the Mars section of In the Wake of Poseidon rounds out the show), other material here shows a somewhat more overtly psychedelic side to the band which was already fading away; that said, the concluding blast of Mars and the opening thunder of 21st Century Schizoid Man reveal that a band of rare power was already out here.

This was recently reissued on the Complete 1969 Recordings boxed set with about as much audio tidying-up as can viably be expected; if sound quality is a factor and you have deep pockets, and you are extremely interested in this period of the band, I'd recommend that set. The lone CD, if you can get it at a good price, may be more the speed for folk who don't need multiple live releases from the 1969 lineup of the band, but do want to have a listen to how they sounded before In the Court of the Crimson King came out and are interested in this specific performance due to the Stones connection.