Is/was Purcell part of the "folk process" ?

This "folk process" you speak of is the common state that ALL music exists in, and certainly Purcell was engaged with Musical Tradition on all levels - but in terms of the microcosms of folk - well, he supplied the original tune to Mad Tom of Bedlam in Pills To Purge Melancholy (possibly) now all but rejected in favour of a more - er - folky one. He had a hand in all sorts of other stuff from Scots Airs to Folkish Themes (Lillibulero / Rigadoon / Harvest Home (Your Hay it is Mowed) which I often hear sung in folk clubs...) and referenced the vernacular & popular genres commonly in his work. He was truly a master, youthful, vigorous, prolific, opening new ground as passionately as he ploughed over the old. His equivilent in today's world (present era = my lifetime & yours) would maybe be Frank Zappa...