Privy Council of Northern Ireland in the context of Privy Council of Ireland

The Executive Committee for Northern Ireland was the government of Northern Ireland created under the Government of Ireland Act 1920. Generally known as either the Cabinet or the Government, the executive committee existed from 1922 to 1972. It exercised executive authority formally vested in the British monarch in relation to devolved matters.

Under the Act as originally enacted, the "Executive Committee for Northern Ireland" was an executive committee of the Privy Council of Ireland consisting of the ministers appointed by the Lord Lieutenant of Ireland to head departments of state. Ministers so chosen did not have to be members of the Parliament of Northern Ireland but were required to become members within six months. The Irish Free State (Consequential Provisions) Act, which came into force in December 1922, replaced the Lord Lieutenant and Privy Council of Ireland with the Governor of Northern Ireland and Privy Council of Northern Ireland.

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 of Ireland, 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 suspended in 1972 and then abolished in 1973, 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 of Northern Ireland 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.