It may seem like the group Procol Harum is/was a one hit wonder with the smash hit "Whiter Shade of Pale", but they actually put out several good albums. Led by Gary Brooker on piano and vocals, an illustrious group of musicians passed through their ranks, not least of which was Robin Trower. In addition we have Matthew Fisher, Chris Copping, Dave Ball, David Knights, Tim Renwick and others. They had steady output from 1967 to 1975. The remarkable thing about them is that they pioneered Prog. Rock in many respects by blending classical, blues, rock n roll to create a unique sound. Lyricist Keith Reid was an essential part of the band, leaving Brooker with most of the musical compositions. By 1977, they had suffered the fate of many bands of the day, collapsing under their own weight. In the meantime, they created a rich musical tapestry that was certainly ahead of it's time. BTW, John Lennon and George Harrison were huge fans of Whiter Shade of Pale.