Quoted in The Beatles Anthology (Paul) ↑

Figuring out a particular note

Once, when George Martin was figuring out what a particular note was in “A Hard Day’s Night,”… I remember his saying to John: “It’s been a hard day’s night and I’ve been working… Is that a 7th, or another note, or is it somewhere in-between?” John would say, “It’s between those two.” And George would have to put down “blue note” or something.

Paul McCartney, as quoted in The Beatles Anthology