In 2001, a guest posted this:

"Additionally, there is an air attributed to Rory Dall O'Cathain called "Aisling an Oigfhir" (The Young Man's Dream) found in Bunting's 1796 collection, which predates Petrie. Some have suggested this as the "original" tune/air which developed into what we know today as the "Londonderry Air"."

That tune, 'the Young Man's Dream' can now be heard and downloaded at this site:

http://pybertra.free.fr/ceol/tunes.htm

(Do a search - Cntl F - for 'young')

I am not convinced that this tune and the Londonderry Air are related. Yes, there's a mild similarity, but lots of tune have that. To me, the important thing is that the 'Dream' lacks the big jump to the tenth ("for I'll be H-E-E-E-R-E")
which makes the Londonderry Air so distinctive and so cloying.

That jump makes the song so hard to sing that I suspect it was written for an instrument, and an instrument only. Violin or harp, perhaps.

The other tune simply goes up to the tonic and ends on it. Nothing unusual there.

I'm collecting songs to play on the flute. I'll think I'll go see how the new tune works out. So Guest, after 10 years, thanks for the info.