The Peniarth 22 manuscript is, except for the last four pages, a fifteenth-century copy of Brut y Brenhinedd, the Welsh translation of Geoffrey of Monmouth's Historia Regum Britanniae; it was penned in 1444 by one Dafydd ap Maredudd Glais. It belongs to the Dingestow family of manuscripts, which in turn is related, in part, to the Llanstephan Version and Liber Coronacionis Britanorum manuscripts, although the detail of this relationship - and that of the Dingestow manuscripts to one another - still begs a number of questions. Peniarth 22 itself is very similar to, though not a copy of, the early fourteenth-century NLW 3036B manuscript. But there are differences in the orthography, and to a lesser extent in the grammatical constructions used by Dafydd which shed light on the changes that were being gradually adopted in the fifteenth century. This is particularly true of the last four pages, which contain Dafydd's own translation of a Latin chronicle, which comprises a continuation of the Brut. While incomplete, largely formulaic and in parts illegible, it includes detail of historical as well as linguistic interest. Dafydd himself, far from being an institutional scribe, led a colourful life including both murder and public service in fifteenth-century Aberystwyth. But he was not, as previously thought, a cleric.