Procol Harum are an English rock band formed in 1967. They contributed to the development of symphonic rock, and by extension, progressive rock. Their best-known recording is their 1967 hit single "A Whiter Shade of Pale", which is considered a classic of popular music and is one of the few singles to have sold over 10 million copies. Although noted for its baroque and classical influence, Procol Harum's music also embraces the blues, R&B, and soul.
As always, Procol Harum were one of the most interesting bands to prevail through the late 60s into the 70s and beyond. They provided much of the basis from which took its cue, and they have often been associated with the beginnings of the Prog-Rock Movement, although they were initially labelled an “” band, because of the borrowings from in their debut single, .
In March of 1969, David Knights and Matthew Fisher exited the lineup shortly after finishing work on the group's new album, A Salty Dog, preferring management and production to the performing side of the music business. Knights' departure opened the way for bassist Chris Copping to join Procol Harum (thus re-creating the lineup of ), playing bass and organ. Another American tour followed the next month, and in June of 1969 A Salty Dog was issued. This record, considered by many to be the original group's best work, combined high-energy blues and classical influences on a grand scale, and returned the band to the U.S. charts at number 32, while the title song ascended the British charts to number 44. The album subsequently reached number 27 in England, the group's first long-player to chart in their own country.