Bassist John Gustafson was a member of the Merseybeat band The Big Three in the early 60s. With organist Peter Robinson, he first joined up with drummer Mick Underwood in Episode Six. That lineup, however, proved to be short-lived, as the trio went off to form Quatermass in July 1969. The band derived their name from Professor Bernard Quatermass, a character from the first science fiction program on the BBC in 1953. They signed to EMI's Harvest label and their debut was recorded at EMI Studios.

King Crimson imploded after their US tour in late 1969. Ian McDonald and Michael Giles had too much, too soon and would depart to record an eponymous record. Similarly, Greg Lake had met up with Keith Emerson while on tour, and agreed to form a band upon their return to the UK. Thus, Robert Fripp and Pete Sinfield were left with the reins of the band, and faced the task of recording the follow-up-though both Lake and Giles did make contributions to the album, with the latter's brother Peter Giles adding bass. With all the upheaval, little new material was written.

Prior to the release of their third album, Jethro Tull scored another two Top 10 singles in the UK with "Sweet Dream" b/w "17" and "Witch's Promise" b/w "Teacher." The flip side of the latter single would become an FM radio staple in the US, where the band's success prompted their first headlining American tour. With Benefit, Jethro Tull puts the cap on their initial period, defined by their classic bluesy sound.

Organist Vincent Crane and drummer Carl Palmer were first paired in The Crazy World of Arthur Brown. They split off during a US tour in 1969, and returned to England and formed Atomic Rooster (1969 was the Year of the Rooster in the Chinese Zodiac). According to legend, it was during a psychedelic experience that Crane first envisioned the "rooster," and after which his subsequent psychiatric problems began to surface. Crane was a huge fan of James Brown, while Palmer was into Buddy Rich; bringing both influences to Atomic Rooster imbued the band with its unique character.

Following the release of The Aerosol Grey Machine, careful manipulation from Charisma label founder Tony Stratton-Smith released Peter Hammill from his contract with Mercury Records, allowing Van der Graaf Generator the freedom to join the Charisma stable of artists. Hammill and Hugh Banton then reunited the band, with Guy Evans recruiting bassist Nic Potter from The Misunderstood. Yet the arrival of sax player David Jackson, previously with Chris Judge Smith in Heebalob, was when all the pieces fell into place for the band.

In 1968, Deep Purple scored great success in America with a cover of Joe South's "Hush," but their three albums for the Tetragrammaton label were patchy at best. Although the musicianship was high, with Jon Lord's classically-inspired organ breaks and Ritchie Blackmore's arpeggio runs and big riffs, they had a 60s-sounding vocalist in Rod Evans. Rocking-out Colosseum style, the instrumental "Hard Road (Wring That Neck)" from Book Of Taliesyn was arguably the best nugget from that period.

The core members of Colosseum first appeared together (according to rock cartographer Pete Frame) as Bluesbreakers #89, on John Mayall's Bare Wires album. After Mayall broke up that short-lived lineup, drummer Jon Hiseman reunited with bassist Tony Reeves and saxophonist Dick Heckstall-Smith, adding childhood friend and organist Dave Greenslade, while guitarist/singer James Litherland was recruited after an extensive search. Reconstituted as Colosseum, Hiseman assembled one of London's first (and finest) jazz-rock hybrids. Their loud and powerful debut is an absolute stunner.

After ending 1968 with the rockin' single "Second Generation Woman" b/w "Home Town" (again without chart success), Family enlisted IBC producer Glyn Johns for their next album, Family Entertainment. Best known for his work with The Rolling Stones, Johns stripped back the psychedelia, bringing both the rhythm section and Charlie Whitney's guitar to the forefront. The record is still a primarily acoustic affair, but with a more potent rock ‘n' roll feel.

Following their second 1968 US tour supporting the Jimi Hendrix Experience, Soft Machine effectively broke up. Robert Wyatt stayed in the US, while Mike Ratledge returned to London and Kevin Ayers sold his bass and departed for Ibiza, where he would eventually launch a moderately successful solo career. But a recording commitment to Probe Records prompted new sessions for the band, this time at London's Olympic Studios. Wyatt and Ratledge invited roadie Hugh Hopper to join up.

Here begins the musical quest of Van der Graaf Generator. Led by the indefatigable Peter Hammill, he would divide his time between leading VdGG and a prolific solo career over the next decade; though where those lines separate could at times prove difficult to identify. The band had already been through a couple of iterations by the time it got around to recording The Aerosol Grey Machine. Hammill and Chris Judge Smith first formed the band with organist Nick Pearne in 1968 while still at Manchester University.