Prime Minister of Northern Ireland

Prime Minister of Northern Ireland
Arms of the Executive Committee
Nominator	House of Commons
Appointer	Governor of Northern Ireland
Term length	At Her Majesty's pleasure so long as General Elections are held no more than five years apart.
Inaugural holder	Sir James Craig
Formation	7 June 1921
Deputy	Deputy Prime Minister

The Prime Minister of Northern Ireland was the head of the Government of Northern Ireland between 1921 and 1972. No such office was provided for in the Government of Ireland Act 1920, however the Lord Lieutenant, as with Governors-General in other Westminster Systems such as in Canada, chose to appoint someone to head the executive even though no such post existed in statute law. The office-holder assumed the title Prime Minister to draw parallels with the Prime Minister of the United Kingdom. On the advice of the new Prime Minister, the Lord Lieutenant then created the Department of the Prime Minister. The office of Prime Minister of Northern Ireland was abolished in 1972, along with the contemporary government, when direct rule of Northern Ireland was transferred to London.

The Government of Ireland Act provided for the appointment of the Executive Committee of the Privy Council by the Governor. No parliamentary vote was required. Nor, theoretically, was the Executive Committee and its prime minister responsible to the House of Commons of Northern Ireland. In reality the Governor chose the leader of the party with a majority in the House to form a government. On each occasion this was the leader of the Ulster Unionist Party, such was the UUP's electoral dominance using both a simple plurality and for the first two elections, a proportional electoral system. All Prime Ministers of Northern Ireland were members of the Orange Order.

The Prime Minister's residence from 1920 until 1922 was Cabin Hill, later to become the junior school for Campbell College. After 1922 Stormont Castle was used, though some prime ministers chose to live in Stormont House, the unused residence of the Speaker of the House of Commons.