Why did New Zealand change to MMP?
1. Election results
New Zealand's FPP electoral system was finally established in 1913. After a period of adjustment, the Labour Party and the National Party had emerged by the mid-1930s as the two major political parties.
However the well-known effects of the FPP voting system began to be felt from the mid-1950s when the Social Credit party began to gain significant electoral support across the country but without winning many seats. In the eight general elections from 1954 to 1975, Social Credit gained an average of 9% of the vote but won only 1 seat, in 1966.417
Mutterings about whether the FPP voting system was fair turned into wider grumblings after the 1978 election because the Labour Party won 10,000 more votes (0.6%) than the National Party but had 11 fewer Members of Parliament (MPs) than National in a House of 92. Social Credit won 1 seat with 16% of the vote.
Labour's policy at the 1981 election was that there should be an authoritative re-examination of New Zealand's electoral system. Its concerns about the FPP voting system were reinforced after that election since once again National won more seats (4) than Labour even though Labour won 4,000 more votes than National. Such results confirmed Labour's suspicions that the way the FPP system was working in New Zealand was biassed against it and strengthened its resolve to review the electoral system as soon as it could. The 1981 election again underlined Social Credit's difficulties; it won 21% of the votes but only 2% of the seats.