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>
A Collection of Beatles Oldies theory, the artwork offered the first clues relating to the alleged demise of Paul McCartney and his replacement in the Beatles by a lookalike, a scenario that is said to have taken place in November 1966 and been facilitated by the group's retirement from live performance. "A Collection of Beatles Oldies" offered the debut album release in Britain for many of the band's singles, although these songs had been available on compilation EPs since their initial release. It also provided the debut release in stereo for these recordings, since the Beatles favoured mono mixes for their singles until 1969. The