The list includes all recognised heads of government, the title of which has included colonial secretary, premier, first minister and prime minister, since the establishment of a responsible government in New Zealand in 1856.
James FitzGerald and Thomas Forsaith, who led unofficial ministries in 1854, are not included.
[1][2] Historically it was not uncommon for New Zealand prime ministers to have little tertiary education, however university attendance has become more common since the 1970s.
However, if Jenny Shipley, who attended the Christchurch Teachers' College, now part of the University of Canterbury, is included, the total rises to four.
Only two prime ministers have held doctoral level education (Daniel Pollen and Geoffrey Palmer).