Evans was working as a communications technician for the Post Office in 1962 when he first heard the Beatles perform at the Cavern Club. He eventually became friends with the band, and was soon hired as roadie.
Evans drove the van for the band on tour, set up and tested their equipment, and then packed it all up again.
When the band quit touring in 1966, Evans continued to be friends with the band and work with them in the studio. Evans even contributed to many Beatles recordings, including lending his voice to "Yellow Submarine", playing the Hammond organ on "You Won't See Me", counting off the measures in the breaks of the song "A Day In The Life", (Evans was also one of the four piano players simultaneously hitting the last note of the song), harmonica on "Being for the Benefit of Mr. Kite", tambourine on "Dear Prudence", trumpet on "Helter Skelter", background vocals on "You Know My Name (Look Up The Number)" and the unreleased track "What's The New Mary Jane".
In the Let It Be film, Evans can also be seen playing the anvil during early verions of McCartney's "Maxwell's Silver Hammer", although he did not play it on the actual recording.
In 1968, Evans discovered the band, Badfinger and signed them to Apple Records.
A despondent Evans was tragically shot and killed by the Los Angeles police on January 5, 1976, due to the police mistakenly thought the air pistol he was holding was a real revolver.