"Host of the Air" has been recorded several times, by the Clancy Bros., Sean Tyrell and Tommy Peoples, and Mitchell, McCreesch and Campbell (put host of the air into the Forum and three threads with mention of these show up).
Sounds like O'Driscoll had a bad dream of someone stealing his gal away- that's a simple-minded interpretation anyway. Otherwise, Pooka, some poeteer will show up with a better explication.
The poem also was in "The Wind Among the Reeds: O'Driscoll