It seems that the original arms of the Bishopric of Derry were a figure of St. Columba imparting a blessing. After the time of the Reformation, the arms used were Azure, three episcopal mitres, Or a device which, it is possible, alluded to the three Dioceses of Derry, Raphoe, and Clougher being held together.
After the Great Siege of 1689, Bishop William King, obtained from Sir Richard Carney, Ulster King-at-Arms, a grant of the Arms which have since been born by the See. These are the same as the See of London, with a harp added.
The Arms of the See of Derry are, Gules; two swords in a saltire proper, the hilts in base Or; on a chief of the Arms of Ireland; Azure; a harp or stringed Argent.
The Arms of the See of Raphoe are, Ermine; a chief per pale Azure and Or; the first changed with the sun in splendour of the last; the second with a cross patee Gules.