Great Seal of Northern Ireland
The seal was designed by Nevile Wilkinson, the Ulster King of Arms, based on the Great Seal of the Realm but with the royal coat of arms bearing an escutcheon with a red cross on a gold field, the basis of the historical coat of arms of Ulster and the sinister banner on the coat of arms of Northern Ireland, also designed by Wilkinson. The first Great Seal of Northern Ireland was provided in time for the state opening of the 1924 session of the Northern Ireland Parliament. Prior to this, the Governor of Northern Ireland (James Hamilton, 3rd Duke of Abercorn) used his private seal instead, as permitted by the 1922 act. The 1924 seal had an image of the reigning monarch, George V. The British practice is to strike a new seal for a new monarch, but Edward VIII abdicated before his Northern Ireland seal had been struck, and the 1924 seal was not replaced until 1938 with one for George VI.
The new seal for Elizabeth II was delivered to the Governor, John Loder, 2nd Baron Wakehurst, on 5 November 1953 at a meeting of Privy Council of Northern Ireland, whereupon the obsolete seal was ceremonially defaced with a hammer by the Clerk of the Council and gifted to the Governor. In 1985 the 1924 great seal was acquired by the National Heritage Memorial Fund for the Ulster Museum. Letters patent by the monarch under the Great Seal of Northern Ireland are used for the following:

All justices of the peace for Northern Ireland are appointed under a single commission of the peace; the commission was issued under the Great Seal of Northern Ireland, whereas the instrument appointing a justice is issued by the Department of Justice without the seal. The Northern Ireland (Miscellaneous Provisions) Act 1945 authorised the preparation and use of a die bearing the same device as the obverse of the seal, and the impression embossed by means of the die on, or on a wafer or other material attached to, a document confers on the document the same validity in all respects as if it had been authenticated by, or passed under, the Great Seal itself. Section 49 of the Northern Ireland Act 1998 makes similar provision for the creation of wafer versions of the Great Seal of Northern Ireland, which is valid for use on letters patent signifying royal assent to bills of the Northern Ireland Assembly. The wafer seals are used by the First Minister and Deputy-First Minister acting jointly. The following are Keepers of the Great Seal, who served as Governor of Northern Ireland (1922–1973)


The following are Keepers of the Great Seal, who served as Secretary of State for Northern Ireland (1973–present).
Uses
The Great Seal of Northern Ireland is the seal used for Northern Ireland.