Earliest ProtoProg Beatles Song?

Yes, it has to be TNK as it's on the same album as "And Your Bird Can Sing".

 

To quote from their wiki page:

"In mid-October 1965, the Beatles entered the recording studio; for the first time in making an album, they had an extended period without other major commitments.Released in December, Rubber Soul has been hailed by critics as a major step forward in the maturity and complexity of the band's music.Their thematic reach was beginning to expand as they embraced deeper aspects of romance and philosophy.Biographers Peter Brown and Steven Gaines attribute the new musical direction to "the Beatles' now habitual use of marijuana", an assertion confirmed by the band—Lennon referred to it as "the pot album", and Starr said, "Grass was really influential in a lot of our changes, especially with the writers. And because they were writing different material, we were playing differently."  After Help!'s foray into the world of classical music with flutes and strings, Harrison's introduction of a sitar on "Norwegian Wood (This Bird Has Flown)" marked a further progression outside the traditional boundaries of popular music. As their lyrics grew more artful, fans began to study them for deeper meaning. "

 

"We Can Work It Out" (also recorded in October 1965) keeps changing tempo and has a waltz in the middle.

 

So in October '65 they were heading in progesque direction (increased complexity, artful lyrics, expanding themes, sitar, and pot)

"Tomorrow Never Knows" wasn't recorded until six months later.

As Knobby explained to us earlier in this sub-forum, Proto Prog was a term used by British vinyls dealers in their ancient catalogues for the specific sound of late 60s - early 70s rock bands who were created that Hammond organ driven sound; Mellotron was also gratefulness but Hammond organ sound was a general rule. If a music is to containing synths, it's not proto prog. Early Deep Purple is maybe the best example of proto prog sound 

Of course, because that term does not mean anything by itself. However, the term was used by dealers for reasons to mark that sound on their lists. As you know, in that ancient time, you're receiving a mail with a dealer's list and then you choose LP, and orderrng. In these lists were only the names of the bands & albums, style, a record company name & price.

 

I  never really thought of the Beatles as doing any 'proto prog', since it did refer to a specific type of style and sound as many have already mentioned,  but they certainly used psychedelic rock with many new approaches to recording and sound effects as in orchestration , etc. But then Tomorrow never Knows, Strawberry Fields , and I Am The Walrus could certainly fit into one's definition of proto prog.

 

icons.  It's interesting to contrast the solo careers of Lennon and McCartney.  Dream #9 by Lennon seems to be

his most prog song.   I'm not saying it's his most "avant garde" song.