This website gives the story of "Waltzing Matilda.": Matilda
The original Ms of Patterson is shown. The words are different from those now commonly sung. Macpherson's arrangement is also shown.
The situation is explained in the posts above, but those interested will find much more at this website. Apparently royalties were payed when the song was played at the Olympics in Salt Lake City (only payable on performances in the USA). As Clarke says, a real nightmare!