Question: Who is Gwrgan Fawr's paternal grandfather?
Sentence (from "Gwrgan Fawr"): This powerful lord, who ruled further west in Glywysing, granted the saint half the fishing rights on the Rivers Usk and Neath in return for the great sword of King Rhun Hir of Gwynedd and a fine new horse with all the trappings.
Relevant evidence: No