The roots of Procol Harum are in a live band led by Gary Brooker called the Paramounts, which were popular performers in the early 1960s. They signed to Parlophone in 1963 (see 1963 in music) and released "Poison Ivy", a moderate British success in 1964 (see 1964 in music). They were unable to recreate this success, however, and the band fell apart in 1966 (see 1966 in music). Brooker began working as a songwriter and soon formed a band called the Pinewoods, who recorded "A Whiter Shade of Pale" before changing to "Procol Harum". With the sudden success of "A White Shade of Pale" and the Moody Blues' "Nights in White Satin", Deram Records became known as the premiere progressive rock label.
Procol Harum's live debut was opening for Jimi Hendrix in 1967 (see 1967 in music), which led "A Whiter Shade of Pale" reaching #1 on the British charts and selling almost as well in the US. The follow-up, "Homburg", was almost as successful, but the LP Procol Harum, was less successful. A series of singles continued charting in the US and UK, though rarely both at the same time, while the band continued adding more classical elements. A Salty Dog (1969; see 1969 in music) was popular among fans, and was their first album to sell well; it is still highly regarded as perhaps their best LP.
During the 1970s, Procol Harum remained more popular than the more inaccessible prog rock bands like Emerson, Lake & Palmer. The band continued in spite of constant line-up changes. They were one of the first groups to achieve success with a symphony, as the album Procol Harum Live with the Edmonton Symphony Orchestra reached #48 in Britain in 1972.
More personnel problems contributed to declining sales in the later part of the 1970s, and finally broke up in 1977 (see 1977 in music). They reunited for a single performance five months later, due to "A Whiter Shade of Pale" being named joint winner (along with Queen's "Bohemian Rhapsody") of the Best British Pop Single 1952-1977 at the Britannia Awards, part of Queen Elizabeth II's Silver Jubilee.
The band reformed in 1991 (see 1991 in music) and released The Prodigal Stranger, but sales were sluggish. A new incarnation of the band, led by Brooker, has continued touring the US since 1992 (see 1992 in music).