Procol Harum was a British Rock/Psychedelic/Progressive band that was formed in the early 1960s. They drew attention with their #1 hit single "A Whiter Shade of Pale", though over time their success declined and they obtained a large cult following.
After the success of their initial studio work, they decided to tour, with their first show being the opening act for Jimi Hendrix in 1967.
The Original (Classical) lineup consisted of Gary Brooker (piano and lead vocals), Robin Trower (guitar), Matthew Fisher (organ), David Knights (bass), B.J. Wilson (drums), and Keith Reid (lyricist), though there were many, many lineup changes before they broke up in 1977.
Point of interest: Procol Harum's "A Whiter Shade of Pale" tied with Queen
's "Bohemian Rhapsody" for Best British Pop Single 1952-1977.