Orthodox Saints of the Pre-Schism See of Rome
CASTULUS and EUPREPIS, (Date Unknown), Roman martyrs of whom nothing is known.
CONSTANTIUS, (Fifth Century), a Roman priest who suffered under Pelagians of whom he was a staunch opponent.
TROJAN (TROYEN), an early sixth century Bishop of Saintes. St. Trojan is remembered as a man of great piety and fervour, was blessed with the gifts of prophecy and heavenly visions, and was revered as a saint even before his repose in 533.
TUDWAL (TUGDUAL), a Welsh monk who went to Brittany and was later consecrated Bishop of Tréguier under the patronage of Childebert I, King of Paris (r. 511–558). St. Tudwal reposed circa 564. There are several places on the Lleyn Peninsula in Gwynedd which commemorate him.
Prior to the Schism the Patriarchate of Rome was Orthodox, and fully in communion with the Orthodox Church. As Saint John of Shanghai and San Francisco +1966 said “The West was Orthodox for a thousand years, and her venerable Liturgy is far older than any of her heresies”.
In many cases there are several spelling versions of the names of saints from the British Isles. I use the Oxford Dictionary of National Biography version as the primary version with the more prevalent version in parenthesis e.g. Ceadda (Chad) of Lichfield.