Did she get it from Martin (ie did he teach her) or did she learn it from a Martin Carthy recording - I think this is an important distinction in context?

There are none that I learned from him, several that I have taken in whole or part from his recordings, and one (of mine) that as far as I know he does not sing but he did say "good song" after my late wife and I played it at our then club when he was the guest, and I did say he was welcome to do it and give him a print of the words.