To illustrate how seriously many of the post-British Invasion bands were approaching the rock idiom by April 1973, you need look no further than Pink Floyd‘s Dark Side of the Moon to see how this “progressive “ rock movement had matured with spectacular results, both artistically and commercially, confirmed by my guests David Gilmour, Roger Waters, and Nick Mason. As early as the Moody Blues’ 1968 Days of Future Passed, which was the result of a combination of new technology ( the Mellotron , which crudely emulated choral and orchestral sounds ) and desperation, an increasing number of British and European bands expanded rock’s canvas musically and lyrically without the slightest consideration to the pop hit mainstream. King Crimson’s stunning debut in 1969, In the Court of the Crimson King , inspired others such as fellow Londoners YES to release Close to the Edge less than a year after their breakthrough album Fragile . While not normally considered a prog-rock band, Traffic nevertheless had their biggest seller in 1972 with The Low Spark of High Heeled Boys , built around the 11 minute hypnotic title song which featured electronically synthesized saxophone, while Trilogy from Emerson , Lake , and Palmer as well as Foxtrot from the Peter Gabriel-led Genesis, had critics raving and cash registers ringing.
Of course all of this would culminate in Spring 1973 with the incomparable Pink Floyd album The Dark Side of the Moon , an iconic masterpiece which long ago threw off any binders imparted by categorization merely as progressive rock , but not before both Jethro Tull’s Thick As a Brick and the Moody Blues’ Seventh Sojourn would each rack up #1 international sales in 1972. – Redbeard
(L-R: Nick Mason, David Gilmour, Roger Waters, Rick Wright)