Hammond met
Ian Anderson in
grammar school and formed a band with him and future Jethro Tull members
John Evan and
Barriemore Barlow. After school, he gave up music he went to study painting. Meanwhile, Anderson formed
Jethro Tull and wrote several songs about his friend's idiosyncrasies, such as "
A Song for Jeffrey" (on the album
This Was), "Jeffrey Goes to
Leicester Square" (
Stand Up) and "For Michael Collins, Jeffrey and Me" (
Benefit). Hammond is also mentioned in the lyrics of the
Benefit track "Inside". In January 1971, when
Glenn Cornick left the band, Anderson talked Hammond into joining Jethro Tull. In addition to playing bass, he narrated the surreal piece "The Story of the Hare Who Lost His Spectacles" on the album
A Passion Play. He also received credit, along with Anderson and Evan, for writing the piece. In a similar vein, he wrote and performed the words for "Sealion II", an alternate version of the
WarChild song recorded during the same sessions as the album, which was first released on
Nightcap in 1993 and later included on the 40th anniversary edition of
WarChild. During his time in Jethro Tull, Hammond wore a black-and-white-striped suit and played a matching bass guitar; He burned the suit in December 1975 upon his departure from the band. According to Ian Anderson's sleevenotes for the 2002 reissue of Tull's
Minstrel in the Gallery, Hammond "returned to his first love, painting, and put down his bass guitar, never to play again." His replacement as bass player was
John Glascock, a professional musician from the band
Carmen. Hammond has developed a second career as a landscape painter. ==Later musical appearances==