Anyone got links to sites discussing Unacommpanied Traditional English Singing online?

I'm still perplexed at a seeming dearth of easily accessible information about this subject in the public domain...

Jim C, I look forward to hearing more on the 'promised' teaching material front.

And Cap'n - Cheers, I bookmarked your YouTube channel long ago. In fact I learned (if I remember rightly?) Bushes and Briars from your rendering of it...