Between 1946 and 1975, the Secretary of External/Foreign Affairs also served concurrently as the Permanent Head of the Prime Minister's Department. For much of this period, several New Zealand Prime Ministers including Peter Fraser, Walter Nash, and Keith Holyoake held the External Affairs portfolio. MFAT had no relation to an earlier Department of External Affairs, which was responsible for administrating New Zealand's South Pacific island dependencies of Niue, the Cook Islands, Tokelau, and Samoa between 1919 and 1943.
From 1946 to 1975, the Secretary of Foreign Affairs held a dual role as the head of the Prime Minister's Department. Several New Zealand Prime Ministers, including Peter Fraser, Walter Nash, and Keith Holyoake, oversaw both roles during this period. The Ministry for Foreign Affairs (MFAT) was established later than the earlier Department of External Affairs, which managed New Zealand's South Pacific island dependencies from 1919 to 1943.