I was quite taken with the hymn. The text was moving, the tune lovely, and of course, there were Welsh people singing it, so it really came across. I thought, wow, that's a really cool bit of Anglican hymnody. I decided to look it up online.
It's called "I Hear Thy Welcome Voice," and guess what: It's a 19th-Century American song, written for the Holiness camp meeting circuit. I was flabbergasted. I need to see if it's in any of the songbooks in my collection. And I'm thinking I need to work out the guitar chords and use it.
Here it is. https://www.hymnal.net/en/hymn/h/1051