Always feels to me like it could/should have been a "normal" Anthony Phillips album (I.e. not in the PP&P series). It just has the flow of a proper album. It's one of his best, and I'm convinced if it had just been called "New England" and marketed as the new AP album it might have done better commercially.
Expanding on that, I feel like there was a bit of mission creep with the PP&P series. The first few were collections of various unreleased bits and pieces. Then later you get releases like PP&P V - "Twelve" which seems to have been a single project conceived and recorded as an album. Why put that in the series?