Formal structure of "Sergeant Pepper's Lonely Hearts Club Band"
Verse 1 0:23-0:43
Middle 8? 1:26-1:38*
Verse 2 1:38-1:58
Comments: The introduction is again in two parts (similar to [6b] "A Taste Of Honey",  "Thank You Girl",  "Little Child", [14b] "Roll Over Beethoven",  "You Can't Do That", and [31b] "Matchbox",  "Baby's in Black", [38b] "Mr. Moonlight",  "I Feel Fine", [46e] "Honey Don't",  "Ticket to Ride",  "Run For Your Life",  "Norwegian Wood (This Bird Has Flown)",  "Day Tripper",  "If I Needed Someone",  "Tomorrow Never Knows",  "Love You To",  "Paperback Writer",  "Rain, and  "Taxman",  "I Want to Tell You", and  "She Said She Said"), with the first 12 seconds consisting of nothing but background noises, and the next 11 seconds featuring the "music proper", which establishes the tempo, tonality, and character for the song and ultimately the rest of the album.
The section right after verse 1 is clearly a break (which I defined as "a break for the singer") as the band instruments play, temporarily relieving the lead vocals. Tonally, during this break, the song tonicizes C major instead of G major. This same chord progression and thus tonicization also occurs in the section right after the chorus, however in this case the band is replaced with two- and sometimes three-part vocal harmony. Clearly this is not a break since it's not "a break for the singer", but at the same time is equally clearly the same music (i.e. the same chords, same bassline, same drum beats - just with vocals replacing the band). Furthermore, the fact that these sections both tonicize C major suggest that they function rather like a middle 8 (which I defined as "a contrasting section in the middle of a song"). With their location in the middle of the song, and in tonicizing a different key, clearly these passages fit the criteria of middle 8. In this way, the defining characteristics between break and middle 8 are blurred, and for these reasons I have included question marks in the above analysis.
Regardless of choices in diction and defining characteristics of formal sections, the break/middle 8 sections in question are nearly identical, and that relation creates a clear palindromic structure for this track:
"Sgt. Pepper" is the fourth Beatles song to date to employ a palindromic formal structure, the others being  "I'll Be Back",  "Strawberry Fields Forever", and  "When I'm Sixty-Four".
This blog is a workshop for developing my analyses of The Beatles' music.