Peter, here's a link to this song at one of my favorite Internet sites (because it gives sheet music.) I have the book though, so I don't use this site much. Let me know if you want me to analyze this for chords. It seems to be pretty basic...Eb, Ab, Bb and a cmin and amin thrown in. I'm not sure where your "sad" chord is in the last line. I suspect it's not in this arrangement.

The Book of a Thousand Songs Blue Bells of Scotland