Williams in his theological beliefs was a follower of the
Oxford Movement. Whilst serving at Holywell, he was one of four commissioners who prepared the revised edition of the Welsh Prayer Book of 1841. Later, while pastor at Amlwch on Anglesey, he translated the Book of Psalms into Welsh metre, entitling it
Y Psallwyr, neu Psalmau Dafydd (The Psalter, or the Psalms of David). He wanted to make psalm singing more popular by using a wider variety of metres than Prys had done. He completed his psalter in 1850 and dedicated it to the Marquis of Lansdowne. In 1851 he began editing the new folio edition of the Welsh Bible for SPCK. ==Works==