I've not had the pleasure of dancing to Fendragon yet. Hope I do soon (I love your cello).

On Set tunes,
A) Many 'social dance' bands change to alternative tunes part way through, then back to the original to finish.
B) In the eighteen & nineteenth century publishers DID name dances after the tunes: confusing in a different way, as there were - Different dances in different books.
Same tune different names
Same name different tunes
C) Some ceilidh dances are also wedded to their own tune and cause confusion when the band changes. E.g. Blaydon Races which has a swing at the end - tempting to go into a promenade unless the tune takes you back to forward and back.
D) Some ceilidh dances work with some of a particular type of tune but not others. It is good if the caller is given a set-list in advance and can pair her most often called dances with tunes on the list.