In addition to being very similar to one way of "The Galway Shawl", the air is also like that of "[Sweet] Omagh Town". Further to Rapaire's posting just above, I've heard those lines as,

"In the early mornin,
The Screws were bawlin,
'Get up, ye bowsey and clean up your cell'..."

and I think it was a recording of BB himself singing.