I get the impression that every so often, I get pulled back toward the ap Huw manuscript, get very excited about it, and then totally forget about it.
I've got Karen Marshalsay's book, for instance, on the ap Huw ornaments. I've even managed to learn a few. But it's the cerdd dant, the 24 measures of Welsh music, that have my attention this time. I'm still dipping into it, but the cerdd dant are represented in a binary notation: 11001011, for example. 1's are home notes (or figures of notes?), 0's are aways. Home is tonic; away is a step below tonic. This page talks about it some more, and gives an example of a Scottish pibroch bagpiping tune that follows the 11001011 pattern. Each 1 is a rising third from home, and each 0 is a rising third from away.
Don't that look just like the rising fifths I do (on home and away) to accompany poetry recitation?
So I hauled out the harp and tried the same 11001011 pattern, using fifths instead of thirds, and throwing in some grace notes via thumb chokes (descending grace notes) and fallings (rising grace notes - the thumb is the thing that's falling) per Marshalsay's book. And HEY WOW that's loads better than plain old re-la, re-la, ti-so, ti-so etc. and so forth.
Here's a link soup on cerdd dant. I want to come back to this and dig a little deeper, try to find the actual 24 patterns. (Master Gregory Blount of Isenfir has the original manuscript scanned, because of course he does, so I can go get that if no one's conveniently transcribed it elsewhere yet.)
Simon Chadwick's list of books on Welsh music
Cerdd Dant Society of Wales (I think?)
A Tolkien fan's article on cerdd dant, with good resources
Wire Branch of the Clarsach Society article
Bill Taylor article on it. I have his "Two Worlds of the Welsh Harp" CD, and he's generally considered the leading interpreter of the MS.
Article on musical group Bragod, who've crossed my radar before. Some information on cerdd dant.
A PDF of Chapter 1 of... someone's thesis? on ap Huw?
Edit: Ah, more of the good stuff:
Peter Greenhill's 1995 magnum opus on the MS
Important paper by Bill Taylor, plus the rest of the periodical's contents
Paul Dooley's website (still under construction as of a year ago). Do I have his CD? Dooley is another interpreter of the MS.
Master Gregory's page of resources, including a scan of the MS
Edit again:
Bragod's website has a huge tutorial. Huzzah! The 24 measures!