This question has cropped up a few times--most recently on this thread, but nobody seems keen to answer it.

The question:
Why do people say "a cappella" when, up till a few years ago, everyone said "unaccompanied"?

In the UK most of the older folkies (which I suppose must include me, on purely chronological grounds) hadn't even heard the expression. Nobody desribes a folk song as "con brio" or "largo" or whatever ...

Comments and opinions please.

Steve