Reluctant as I am to place music artists into categories (akin to a good many here, I enjoy many different styles - as long as it doesn't sound like it was blatantly demographed, marketed, dreamt up in some corporate board room -- you get the idea, because it can be smelled from miles away)....
But I digress - my first experience with Shawn Phillips was in the form of a very lengthy, whispery but disquieting track with orchestral arrangement which was broadcast on the (now sadly scarce on my local airwaves) Hearts of Space program. "ThisWas", you no doubt know the piece I'm attempting to describe. With some artists having entries in the archives of which I might be dubious
, I say "what the hey" - call it prog. In an autumny Nick Drake sort of way... yeah, Canterbury, don't they call it?
In summary: It's ALL prog, except when it's not.