Not a lot to go on here - I can think of 2 Scottish musicians who were soloists , playing 5-string banjo, playing Scottish Folk Clubs in the 1980s - Iain Mackintosh [ but he would have been in his 50s in the 1980s ], and Ian Walker.
"Muckle Ado" I think were from Fife in Scotland. My brother made one of their cassette tapes which I may still have somewhere. I'll have a look when I get the time. The mystery song might be on it, you never know. But if this is a search for a solo artist, they are irrelevant to this discussion.
What is meant by "folk songs from the Isles" ? - which Isles ?
The 4 songs you mention are Irish [as far as I know ], Scottish and American with one possibly a contemporary original. Not really any clues to the singer's origin from repertoire.