Dave, it's copyrighted to Harmony Music in 1962 -- but could have been written before then, obviously.

Pete Seeger had done a concert in Glasgow's St Andrew's Halls in 1961(?) and had stayed with Norman Buchan, during which time he had met and been impressed by Matt; he reputedly left the instruction to "Keep that man singing" and thereafter organised a concert for Matt in Carnegie Hall, New York the following October. I'm fairly certain that this would have been the impetus to protect his material by copyrighting it, and I know that several songs were printed in the American magazine Sing Out.

With regard to the tunes, I'm no authority but some of his songs are written to recognisable tunes (Is Bingo Bella not based on The Darktown Strutters' Ball?), whereas many of the more lyrical songs seem to have tunes IMHO of Matt's making -- but, like yourself, I'm hoping that there may be someone out there who can reveal Matt's composition process…

(For what it's worth, I once sang Coorie Doon to an audience which included a toddler on its mum's knee; the audience joined in the chorus and we became progressively quieter until the wean fell asleep. Mind you, it was hot and stuffy in the room!)