Note 1403 — Chapter X · THE REIGN OF EADWARD FROM THE DEATH OF THE ÆTHELING TO THE DEATH OF THE KING.[1258] 1057–1066.
Reading edition
I quote literally the Brut y Tywysogion. Its wrong date, 1061, is corrected in the Annales Cambriæ into 1063. “Griffinus filius Lewelini Rex Britonum nobilissimus dolo suorum occisus est.”