Thanks for that, Phil! Considering Bullen's anthology is so highly regarded (and rightly I might add) the actual mentions of them in his other books seem oddly scant. Personally I would have thought that if he was used to hearing chanties he would have referred to them in his books. I'm wondering if he was largely remembering them from his youth.
Here's another possibility, he wasn't that au fait with them although he was aware of their extempore nature and wanted to expose the bulk of what had been published as made up by their anthologists. Just a thought.
Gibb would have a better handle on this.