Revolver (Beatles album) group collective since 1962, and gave them an unprecedented amount of time to prepare for a new album. Writing in "The Beatles Forever", Nicholas Schaffner cites 1966 as the start of the band's "'psychedelic' period" and adds: "That adjective implies not only the influence of certain mind-altering chemicals, but also the freewheeling spectrum of wide-ranging colors that their new music seemed to evoke." Music journalist Carol Clerk describes "Revolver" as having been "decisively informed by acid", following John Lennon and George Harrison's continued experimentation with the drug LSD since the spring of 1965.<ref name="Clerk/Uncut"> Available at Rock's Backpages (subscription required).</ref>
Por Siempre Beatles on the 1966 UK compilation "A Collection of Beatles Oldies", while "The Fool on the Hill", "Strawberry Fields Forever", "Your Mother Should Know", "Penny Lane", "Baby, You're a Rich Man" and "Blue Jay Way" all appeared on the American "Magical Mystery Tour" LP. The latter, while widely available as an import in Britain since 1967, received an official release there through Parlophone in 1976. "I Call Your Name" and "Yes It Is" had been issued on American albums during the 1960s – "The Beatles' Second Album" and "Beatles VI", respectively. All songs by Lennon–McCartney, except tracks 11 and 12 by