In the early episodes, when it seemed like the trio weren't getting hospitality or being welcomed in the Cafe, they'd break out into this song. I'd always get a chuckle when this happened. I've never heard this song before, till after I actually looked it up and listened to it.. I know it's a popular Welsh folk (or spiritual song). Just thought I'd mention it as one of the things that would give a chuckle from the show..