So I can at least assume that the tune which is universally sung today was not composed originally by Thomas Arne or any other operatic composer ... it is a bona fide Anon trad tune. That's all I wanted to know.

I cannot help but be reminded, reading about the tune being altered , and the lyrics being altered, about my deceased grandfather's yard broom, which he claimed was over a hundred years old, and had had only five replacement shafts, and seven replacement brush heads in all that time.