"Copyright would be in the first instance to MacColl if he was first to publish."

That maybe copyright on the pages as printed and on anything in them that stems from MacColl and Seeger's own efforts. If a song or story is reproduced as collected without any editing do they get any ownership of that intellectual property?

If you make up a song and sing it to me and, with your permission but no other sort of agreement**, I put it in a book then anyone photocopying the page will be infringing my copyright and yours. I think that someone learning and singing the song may be infringing your copyright but not mine.

** an agreement or contract could open up a while bag of worms.