Getting it on with Prog

Well I would agree that only the first two albums are truly in the prog vein.
subsequent albums are not bad but not even close to the first two.
Dont know any other prog band at the time who foregoed a guitarist period.
Although I am sure there were some.

Obvious one is The Nice. After O'List left.

By the way, his solo lp is excellent.

Proto prog is where the Hammond organ comes to full bloom and has its day. Guitar is relegated to the backdoor, or not existant at all. Bands on labels like Neon were guitar-less or guitar-muted.

I just got a (duplicate) of Swegas "Child of Light". First track is a cover of Rare Bird, "Beautiful Scarlet"! (A cover of a band from the same immediate time period...and not that well-known either. Which means someone in the band had great admiration for Rare Bird.)

Of course after Graham Field and Ashton left Rare Bird, the sound changed dramatically and was guitar-prominent. More rock than prog.
Still, like Sammmmmy said above, the title track from "Epic Forest" is real good. Maybe reminds of....errr.....Nektar???

I have a Polish Muza press (with complete different cover art)of the second Rare Bird. Well, mostly . This is the tracklist:
sympathy
down on the floor
nature fruits
as your mind flies by
what you want to know
bird on a wing
hammerhead
times

Not prog rock but many recordings done by jazz organist Jimmy Smith also from back in the olden days deliver superbly recorded electric organ front and center (or actually usually more to the left or right).

Many famous Jazz musicians in general from that era were very progressive musically.

Like you say,not prog but progheads' main Jimmy lp want would be "Rootdown". Also one of the rarest.

The prog-sounding lp would have to be "Peter & The Wolf" .

Smith did not use Leslies.