There's a convenient way to chase down an answer to the questions.

You can click on the membername, "Sarah - the - flute," where it is blue-clicky highlighted.

That link will take you to all that member's posts.

There you will observe, as I just did,
that "Morrigan" figures prominently in her postings, early and recent,
where you can read what she has to say about it.

And then there's Martin Carthy.
He is represented by Alan Bearman who has his own website;
the Martin Carthy appearances page on Alan Bearman's website
can tell you where, when, and how. All this stuff is out here
and ready to be looked up.