Greenbelt is not for people like us. It is an Evangelical Rock and Worship Festival.
However, a text from a colleague who is attending has alerted me to something that might make any of us stop and take notice. This year, there is a beer tent, in which people (well, men) spend their time drinking beer and bellowing out hymns. And guess what: all the hymns they bellow out are traditional ones. The text doesn't say whether there is a tape to sing along to, or whether there are hymn books, or whether the drinkers are just blessed with fine memories. The fact that the texter is into the folk scene in a big way suggests to me that this is people singing what they know and what works when people sing, which means traditional tunes which everybody knows.
This (I texted back) is very Catholic. Pre-Reformation, the Parish Ale would have been brewed every time there was a feast day. Post-Reformation, the connection between drinking and celebrating God's Glory is still there, though much stronger among Catholic Christians than elsewhere.
I also suggested that, on being furnished with proof that this is as good as it sounds, I might, just might, be tempted along to a tent evening next year.