Thanks to "Anonymous" on another thread, I've just now located sheet music.  It's at the Levy Sheet Music Collection -search for "allandale" (spelt with an "a").  There are .jpgs of three editions, printed in New York and Baltimore (no dates) with piano accompaniment.  I still don't know where the song originated, but if it were an American composition, that might explain the curious placing of Allandale/Allendale in the Highlands.  Possibly some confusion with the River Annan in Dumfries?

Malcolm