The lyrics are by Joe Mulheron. I just heard Eileen Cullen Webster sing it at a Bloody Sunday commemoration in Derry last night.

The Hot Ash recording can be heard on a few channels on youtube, including https://www.youtube.com/watch?v=_-uBuipj6z8

A published version of the words (Harrowing of the Heart - The Poetry of Bloody Sunday,Guildhall Press 2008) names the Widgery Tribunal in the first line of the last verse.