The Celtic Princess fell for The Prince of Rheged who was ruler of what modern day country? 
Credo (novel):  An epic story of the Christian faith set in 7th Century Britain, it centres on the life of a young Celtic Princess torn between her dedication to God's service and her love for Padric, a Prince of Rheged. Rheged: Rheged (] ) was one of the kingdoms of the "Hen Ogledd" ("Old North"), the Brittonic-speaking region of what is now Northern England and southern Scotland, during the post-Roman era and Early Middle Ages.
i don't know