Donovan's Interpretation Of "Yellow Submarine"

Paul's 1966 song, "Yellow Submarine" was always seen a lightweight, nonsense song.  And because The Beatles invited Marianne Faithfull, Brian Jones, and George's wife, Pattie Boyd in the studio to sing background for the song--something that went against The Beatles' very settled routine of never allowing anyone other than themselves to sing on their tracks, people thought this might be a festive, party song.  And for Beatle researchers, since the song was on our Paul and our John's last album as Beatles and there was--we thought--the suggestion that the band beginning to play on the track might be hinting about new band members on what would be the Sgt. Pepper album--we never thought about a grim undertone for the song.  But Donovan the singer, who knew The Beatles, and--no doubt--knew some of the dire strains going on behind the scenes for the band--believes the song describes a collective life for The Beatles that was much more isolated and miserable.

Donovan gave that assessment of "Yellow Submarine" in an interview he had in 2014 with Howard Stern and he reiterated it in 2016 when he toured the US and Canada.

In the interview with Stern--on Youtube at:  https://wwww.youtube.com/watch?v=hrQhMx_pxS0 , Donovan says at 1:05:53-1:06:49:

"But it's not really a submarine, you know what it . . . the song's about? . . . It's really about the life that they've been now forced in, inside their own lives in the white tower called Beatle frame and not really having any contact with reality out there anymore . . . We're actually insulated and now against the outer world.  It wasn't a very pleasant thing to be . . ."

I found in the UseNet Guide to Beatles Recording Variations version 2, compiled by Joseph Brennan a variant he found in the June 3, 1966 mono version of "Yellow Submarine" where Ringo (?) in the last line of Verse 3 instead of singing "In our yellow SUBmarine" sings, "In our yellow CLUBmarine." 

It was an extremely exclusive club that Paul could not exit alive.