I have just stumbled across these on YouTube from 2019. The piano in the background certainly sounds like it is from "Hymn of the North" and Jarvis provides some further info about it in the interview. It's just a shame that the full song isn't included.
Yeah, apparently bits of the song soundtracked different scenes in the play until the final few minutes when the whole cast sang the entire song together. I'd love to hear that version to see how it compares.
I wonder if JC changed any of the lyrics afterwards as it sounds as though some may have been quite specific to the characters/narrative. If he has, I guess it bodes well for a future Pulp/Jarv Is.../solo release. Fingers-crossed.