St. Patrick liked to follow true orthodoxy. Patrick later returned to Ireland, where he once was a captive. Amator Bishop Auxerre ordained him a priest and the church flourished during his life. After St. Patrick's death, Rome turned against the Celtic Church, because he followed the Coptic teaching and practiced what he learned in Gaul. Differences were mainly in the Liturgy and Baptism as the Egyptians followed the Church of Jerusalem and not Rome.
Bishops officiate in vestments of oriental character, that is in gold and silver.
They fast on Wednesdays and Fridays. They have daily prayers, Mattins, Vespers etc. Monks stay in separate cells and not in common dormitory. Baptism by immersion. Rome considered these as an unacceptable Irish customs and vigorously attacked the Celtic Church.