He was one of those roman catholics.
Since he was around
way before Rome exerted its authority over the British Isles, that's a pretty daft thing to say. You can call the early Celtic Church Orthodox if you like, but to call it RCC is highly misleading if not false.
I think you are wrong on your history ebia at least if the following article excerpt from the Catholic Encyclopedia is accurate.
St. Patrick
Apostle of Ireland, born at Kilpatrick, near Dumbarton, in Scotland, in the year 387; died at Saul, Downpatrick, Ireland, 17 March, 493.
He had for his parents Calphurnius and Conchessa. The former belonged to a Roman family of high rank and held the office of decurio in Gaul or Britain. Conchessa was a near relative of the great patron of Gaul, St. Martin of Tours. Kilpatrick still retains many memorials of Saint Patrick, and frequent pilgrimages continued far into the Middle Ages to perpetuate there the fame of his sanctity and miracles.
In his sixteenth year, Patrick was carried off into captivity by Irish marauders and was sold as a slave to a chieftan named Milchu in Dalriada, a territory of the present county of Antrim in Ireland, where for six years he tended his master's flocks in the valley of the Braid and on the slopes of Slemish, near the modern town of Ballymena.
Admonished by an angel he after six years fled from his cruel master and bent his steps towards the west. He relates in his "Confessio" that he had to travel about 200 miles; and his journey was probably towards Killala Bay and onwards thence to Westport. He found a ship ready to set sail and after some rebuffs was allowed on board. In a few days he was among his friends once more in Britain, but now his heart was set on devoting himself to the service of God in the sacred ministry.
No sooner had St. Germain entered on his great mission at Auxerre than Patrick put himself under his guidance, and it was at that great bishop's hands that Ireland's future apostle was a few years later promoted to the priesthood. It is the tradition in the territory of the Morini that Patrick under St. Germain's guidance for some years was engaged in missionary work among them. When Germain commissioned by the Holy See proceeded to Britain to combat the erroneous teachings of Pelagius, he chose Patrick to be one of his missionary companions and thus it was his privilege to be associated with the representative of Rome in the triumphs that ensued over heresy and Paganism.
Patrick's thoughts turned towards Ireland, and from time to time he was favoured with visions of the children from Focluth, by the Western sea, who cried to him: "O holy youth, come back to Erin, and walk once more amongst us."
Pope St. Celestine I entrusted St. Patrick with the mission of gathering the Irish race into the one fold of Christ. Palladius (q.v.) had already received that commission, but terrified by the fierce opposition of a Wicklow chieftain had abandoned the sacred enterprise. It was St. Germain, Bishop of Auxerre, who commended Patrick to the pope. Patrick on his return journey from Rome received at Ivrea the tidings of the death of Palladius, and turning aside to the neighboring city of Turin received episcopal consecration at the hands of its great bishop, St. Maximus, and thence hastened on to Auxerre to make under the guidance of St. Germain due preparations for the Irish mission.
It was probably in the summer months of the year 433, that Patrick and his companions landed at the mouth of the Vantry River close by Wicklow Head.
St. Patrick continued until his death to visit and watch over the churches which he had founded in all the provinces in Ireland. He comforted the faithful in their difficulties, strengthened them in the Faith and in the practice of virtue, and appointed pastors to continue his work among them. It is recorded in his Life that he consecrated no fewer than 350 bishops.
You can read the whole article at
http://www.newadvent.org/cathen/11554a.htm
