As a regular attendee of sessions in the North of England I have a few questions about the phenomenon of unaccompanied singing:

When did it start? Obviously people have always sung to themselves but what is the history behind someone singing to an "audience" unaccompanied? Historical visual references almost always show some form of musical accompaniement (even if it's just someone beating a drum).

Does anyone actually like it? I get the feeling it's something people feel they ought to like rather than actually liking!

Why do people at sessions shut up & listen to a singer but when someone with, for example, a guitar does something everybody starts/carries on talking?

Have there ever been any (genuinely) commercially successful purely unaccompanied singers?