The word "old", when a prefix in many songs, has the D sound dropped to make it easier to sing, such as "Ole Joe Clarke or "Ole Dan Tucker. In Dublin, it is pronounced Aul, sounding like Owl, though often extended to two syllables, such as OW-will, or Ow-well. Listen to any Dublin singer singing "Sez my Aul wan to your aul wan, will ye come to the Waxies Dargle."
It then became used as a general prefix, which doesn't necessary mean old, such as the greeting" Howya, me Aul flower", or "go 'way, ye Aul bollix" etc. Spellings differ in attempting to capture the sound, and though it may be spelt Auld or Ould, the d is silent in pronunciation.
The biographer of Brendan Behan who claims Brendan did make some effort to pay Dicky for the song wsa Michael O Sullivan, and this is mentioned way back on this thread.
Keep up the good work, Tom, me aul flower.