Actually the primary subject matter of my musings (about Welsh names, as variously pronounced and spelled by people whose native language wasn't Welsh, or even Celtic) is largely covered in this article, found elsewhere on this site:

http://www.forest-of-dean.net/downloads/Stories_Articles/Life_in_Hewelsfield_and_Brockw...

That does contain a fairly debatable assertion that Hewelsfield derives from "High wold," rather than "Hywel" (although Powell is from "ap Hywel"). Anyway, it's a very interesting article.