In the NZ press, I read that this election is "Labour's worst defeat since 1928", based on winning 27.1% of the vote.

This is nonsense. It is Labour's worst defeat, bar none. The 1928 result (26%, 19 seats out of 80) was a victory, with a gain of 7 seats, though it was followed by a strategic error : support for a minority Liberal government, which no doubt delayed  their obtaining a majority : they made minor gains in 1931, then, from opposition, won in a landslide in 1935.

_{It is rightly acknowledged that people of faith have no monopoly of virtue - Queen Elizabeth II}