sorry about the formatting last time, guess I have to doublespace to get line breaks: Here's what I get so far, from y'all and from rec.music.celtic:
O WALY WALY: 1725
WILD MOUNTAIN THYME: 1796 (from 24 Scots Songs, probably predates collection)
AULD LANG SYNE: 1700s somewhere
BUNESSAN (tune for Morning Has Broken): Got as far back as early 1800s - songs "Child in the Manger" and "Leanabh an Aigh".
DANISH AMEN: no info yet
BONNIE GEORGE CAMPBELL: no info yet
Didn't understand the "Child #210" entry above -dense of me, sorry.
Thanks everyone, have a great holiday.