St. Merryn, properly St. Meirchion, was St. Seiriol's youngest brother. He lived on the Lleyn Peninsula just north of Rhydlios where the remains of St. Merin's Church can be seen today. He later moved to Bodfelin on Ynys Mon (Anglesey) before emigrating to Brittany. On his way he stopped off in Cerniw (Cornwall) and founded the church of St. Merryn near Padstow. He was a zealous missionary in Little Britain where churches are dedicated to him at Lanmerin and Plomelin. He is often, but should not be, confused with King Meirchion of Meirionydd.