Latin text of Welsh law, which was known to lawyers active in Gwynedd during the 13th century. This text or a related one may have provided the basis for the Latin text in London, British Library, MS Cotton Vespasian E xi, which refers to matters relating to both Gwynedd and south-west Wales. It has been suggested that the Llyfr y Tŷ Gwyn text became known in Gwynedd through the agency of Cadwgan, bishop of Bangor (1215-1236) and abbot of Whitland before that.