My mother had a venerable book of sheet music when I was a child. I'm sure it's still in her piano bench. It was printed in the late nineteenth century, and contained many curiosities, among which was a version of "The Londonderry Air".
Evenings, the family gathered around the piano, and Momma would play the piano while I sang. I learned and loved "The Londonderry Air" years before I found out that another popular song was sung to the same tune: "Danny Boy". (I think this is what sparked my fascination with tracing the roots of song lyrics back to their historical origins.)
As far as I can tell, "The Air of Londonderry" was copyrighted and published in 1861, but the tune itself predates the lyrics by centuries.
On a side note, I read a funny review once that referred to Mr. Danny Kaye casting a backward glance at "The London Derriere". Tee hee.
Anyway, here are the lyrics, as I remember them, to be sung to the tune you most likely know as "Danny Boy":
Would God I were the tender apple blossom
That floats and falls from off the twisted bough
To lie and faint within you silken bosom
To lie and faint, as that does now.
Or would I were the little burnished apple
For you to pluck me, gliding by, so cold
That sun and shade thy robe of lawn may dapple
Thy robe of lawn, and thy hair's spun gold.
Yea, would to God I were among the roses
That lean to kiss you as you flow between
While on the lowest branch, a bud uncloses
A bud uncloses to touch you, queen.
Nay, since you will not love, would I were growing
A happy daisy, on the garden path
So that your silver foot might press me going
Might press me going, even unto death.