John,
I have used Songs of Scotland - Vol 1 and 11 as a resource for my site and have, I think, around 15 tunes and lyrics from them. (Mary's Dream is one.)
The reason I don't use them as much as I used to is because the scans don't turn out as well as with some of the sources I got more recently (so I have to spend a lot of time editing to get a viable midi). The newer sources also have more history (though Volume 11 has some notes).
I'll have to revist them. Gilderoy intrigues me. The book says it dates back to 1650. Wonder how they came up with that?