Thanks, Steve.

I seem to recall reading long, long ago that American minstrels in their with their blackface and exaggerated dialect would adopt a very formal "recital" style when singing, again for the humor of incongruity.

Unfortunately I can't absolutely confirm this. It would be somewhat comparable what you say about the English music-halls, however.

An unfortunate current example is the rugby version of "Swing Low, Sweet Chariot," sung verbatim but accompanied with gestures that create a bawdy double-entendre where none exists in the words.