I remember the writing session as though it were yesterday: Ringo tapped away on a worn-out Liverpool phone book with two skinny, warped wood drumsticks; George holed himself in the bathroom, humming a tune his band mates refused to help him with, “Mmm my Lord, mmm my Lord.” John stuffed another box of Chiclets gum in his mouth while Paul kept pruning his hair in the mirror with a five-inch black plastic comb he was given by a production assistant when he filmed “A Hard Day’s Night.” Me, I stared out onto the Thames from the second-floor rear window of Apple Records’ offices, piecing to