A while back I "discovered" this recording of a performance of a song that must surely be a close relative to the "Dan Dan" presented by Hugill in SfSS. Thought I'd post it here.

It was recorded in Grenada by Alan Lomax in 1962. Because it is labeled "Jean Jean-o," it is not found on searches for "Dan Dan." However, I had been going through listening to the Caribbean recordings of Lomax and noticed the similarity.

Sounds like they are saying "John John."

http://research.culturalequity.org/get-audio-detailed-recording.do?recordingId=2

And here is a clip that might shed some light on who is meant by "John John"/"Dan Dan"—at least as conceived by these singers.
http://research.culturalequity.org/get-audio-detailed-recording.do?recordingId=2

Perhaps this gets us a closer to what Harding of Barbados sang to Hugill, before Hugill processed it in his mind, Harold tried to write it down, and we readers tried to envision our renditions from the little black dots in SfSS!