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 compilation peaked at number 7 on the UK Albums Chart, where all the band's previous albums had held the top spot. It was also released in some other European countries and, in 1968, in Australia. The album was deleted from the Beatles' catalogue following the reissue of their albums on compact disc in 1987. The Beatles made the decision to retire from live performance in 1966, dissatisfied at playing to audiences of screaming fans, and following a series of controversies that had tarnished the band's image throughout the year. These controversies included the unfavourable reaction to the butcher cover originally