Ah, but the fact Thurstan Peters gave a talk about the 'Obby 'Oss in in 1913 proves it existed in 1913, so we can rule out both Disney (in 1929)and Rick Stein!

You said that the Puritans decried the Helston dances. I presume you mean they explicitly mentioned Helston, rather than decrying dancing in general. That raises the question of whether they mentioned Padstow. If so, proves the celebrations is that old. If not, it doesn't prove anything but does give some indication the Oss might not be as old as the English Civil War.