Cousin of King Deroc of Dumnonia. Monk in Wales. Friend and co-worker with Saint Briarch. Evangelized in Brittany. Founded the monastery of Lan Pabu at Leon, Spain. Bishop of Tréguier (Treher), Brittany. Advisor to King Childebert I. Several sites in the Leyn Peninsula of Wales bear his name.
- Book of Saints, by the Monks of Ramsgate
- Catholic Online
- Our Sunday Visitor’s Encyclopedia of Saints
- “Saint Tudwal of Tréguier“. Saints.SQPN.com. 29 November 2013. Web. 22 December 2014. <>