The dance has the title “Ladie Nellie Wemys” in the original book and uses a tune of almost the same name which is normally spelled “Lady Nellie Wemyss”. The latter spelling is added as an alias.
John Mitchell’s daughter Alison writes:
John was a stickler for detail, and “Ladie” would not have been accidental. However, I can well believe that he took the name from a recording of the tune that just “happened” to use that spelling, instead of “Lady”. Certainly, the two are equivalent; but the title is correct as originally published.