Hmmm, link didn't work.
This is the first I have heard of Pap being in the early shelties. Most experts say the original "blend" was "Yakki dog"- Pomeranian-King Charles Spaniel and Border Collie (known as "working collie" back then as they were a mishmash and had little "type" to them but were judged on ability) with rough collie crosses (both declared and undeclared) added later to improve type.
Hope that link will work later, I am intrigued. Wonder what Charlotte McGowan has to say about this
edited to add. What I found was this. There is specualtion that the "dwarf continental spaniel" -a progenator of the Papillon- is somewhere in the sheltie mix. Others dispute this speculation because of the known KCS involvement. Anyway, it's not that shelties have Pap in them, but that they would carry a fairly close up common ancestry if the DCS inclusion in the sheltie is correct.
also edited for spelling, yegads!