Not that it would matter for my love of a beautiful song if Stan Rogers had actually made a mistake, but I am curious now. 'Ulster defence (also: defense) league' and UDL can be found by a websearch as Jeri has said, but they are neither found on the exhaustive Cain websites on Northern Ireland nor in the online archive of the Irish Times. Furthermore, 'UDL' is not found in any of several acronym dictionaries about Northern Ireland.

Could it be that 'Ulster Defence league' is a loyalist support organisation only found in North America and not in Ulster? Then on the one hand Stan would be right and on the other hand the puzzlement of those posters from or closer to Ulster could be understood easily.

Wolfgang