He is best known for his longtime association with the rock band Procol Harum, which included playing the Hammond organ on the 1967 single "A Whiter Shade of Pale", for which he subsequently won a songwriting credit.

[citation needed] He enrolled for classical training at the Guildhall School of Music,[3] but after a year he dropped out, obtained two Vox Continental organs, and used them on tour with The Gamblers, the backing band to Billy Fury.

Consequently, Gary Brooker and Keith Reid were keen to recruit him for their new group, Procol Harum, and decided to visit him at his Croydon home to discuss the formation of the band.

[6] Furthermore, he felt, after seeing the sheet music to "A Whiter Shade of Pale", that he deserved a co-composition credit for coming up with the well-known introduction and solo passages throughout the song.

[5] While "A Whiter Shade of Pale" was an immediate success, reaching number 1 in the UK charts for several weeks, Fisher doesn't recall the time as being a happy one for the band.

[7] Nevertheless, in response to his lack of co-writing credits (particularly over "A Whiter Shade of Pale"), being at odds with Brooker, Trower and Wilson (who had all grown up together in Southend-on-Sea and previously played in The Paramounts), and still suffering from the death of his father in 1965, Fisher wanted to leave Procol Harum.

He was unhappy with the financial situation of the band, and with Trower's replacement, Dave Ball, and so he left again, this time acrimoniously, to become a full-time producer for CBS.

[9] In addition to his work with Procol Harum, he was producer to Robin Trower, James Dewar and Tir Na Nog (among others); and enjoyed a solo career,[10] being especially popular in Greece, where his 1980 song "Why'd I Have to Fall in Love with You" is considered a classic.

Fisher's Hammond organ playing on pianist David Lanz's instrumental version of "A Whiter Shade of Pale" from his 1988 CD, Cristofori's Dream, helped that album go gold as well.

Fisher's instrumental "Theme From Separation" on his album Journey's End is from that film, and the soundtrack also included an alternate arrangement of the piece for Hammond, bass and harpsichord.