To give [“Please Please Me”] a link with “Love Me Do” (in those days the pop business liked to hear some similarity and continuity between consecutive singles) the plaintive wailing harmonica was featured again, but a perked-up version this time. After the eight or ninth take the Beatles hoped they had succeeded in satisfying their record producer. As George Martin huddled with his engineer in the control room to hear back a couple of the earlier takes, Paul shouted from the studio floor: “What shall we do now?” Facetiously, Martin yelled back: “Why don’t you do ‘Blue Moon’?” To everybody’s great amusement the Beatles bounced straight into an impromptu up-tempo version of “Blue Moon.” Some sanity returned to the session with Martin pointing out dryly that time was limited and if nobody minded too much he’d like to hear another take of “Please Please Me.”

[—from John, Paul, George, Ringo & Me, Tony Barrow]