Dean, perhaps it is that you WISH me to carry on so you can learn the error of your - and pretty well this entire forums - ways (when it comes to proto-prog.)
Not sure Im arsed enough to edify.
If you are serious - go to progressive ears or better yet galactic zoo forum.
What has happened here is what I call "cow bird" - the cow bird waits till another species builds it nest then takes over that nest.
The true meaning of "proto-prog" was laid down maybe as much as two decades before Progarchives came up with vastly generalizing the term to mean basically anything that developed out of psych (not "psyche" guys - psyche is "the soul"), pop and ROCK and embryonically began to wiggle towards what was to be progressive rock.
Think - where you think the TERM first came out of: web forums? I can assure you it did not.
Books on prog?
Of course not - it predated all that.
I lay odds it came out of those old (in some cases, yellow-brown paper) lp dealer catalogues that came in the mail to (serious) collectors.
The true meaning of "proto-prog" is it is simply a DISTINCTIVE SOUND that was pushed to make it easier for collectors to get what they were after.
It is NOT a genre (as progarchives would have it). It was mainly Hammond-organ-driven. (General rule, I would say - if its got synth in it, its not proto.). Mellotron can be there also. It was mainly a UK thing, but American proto CAN be identified.
It was mainly A VERY SLIM PERIOD in music's history, usually '69 but you CAN have clearly identifiable proto in '70 and even further on, due to fact that some countries were bit back in time - remember we are stressing THE SOUND here. The INITIAL appearance of the SOUND on vinyl. So you have "backward" countries like Denmark with (compared to the population number) a surprizing wealth of proto being put out as late as '71.
I repeat. Progarchives has taken the dealer-term , built their nest there, gave it their own spin ; made something other of it.
Perfectly alright, I expect. But I wish they would call it something else other than PROTO prog. (Maybe Burgeoning Prog?)
For instance The Who would NEVER be considered proto - they never had the Vertigo,Dawn,Nepentha - etc record label sound.
And for Progarchives in their "best proto lp " picture section to stress something like Deep Purple "Machinehead" and overlook the only one that is remotely proto, "Book of Talysein". (spelt wrong- yeah, who f**ks) is misleading in the least.
What you are speaking of in this thread is simply pop ,bluesrock , psych and ROCK wot began to merge into the oncoming prog.
Your speaking of something very broad, a parameter . Something that varies in different cases.
Whereas the origional, REAL meaning of protoprog is something extremely select and finite.
I dont want to go into it right now, (because it takes some digging on my part and I gots a lawn to mow), but if you seriously want to know what the proto sound is and why it is IMMEDIATELY recognizable on hearing (although difficult to pin down in words) search old Progressive Ears posts for the list of 100 protoprog lps.