I've just been looking through the earliest version of the ideas in "Fakesong", Harker"'s "Cecil Sharp in Somerset: Some Conclusions" (Folk Music Journal 1972, No. 3). It goes through much the same complaints about Sharp's unreliability, but doesn't use the word "mediation" anywhere that I've noticed. It's a dense slog to get through. As well as the more explicit semiotic language, the more expansive scope of "Fakesong" makes for a much easier read. As do the occasional flashes of sarcasm. Grumbles about technical vocabulary get it dead backwards here.