British political psychology data suggests systematically different personalities for the average green and average labour voter that may transfer to New Zealand. Greens are more than what Paul Keating described them: “a bunch of opportunists and Trots hiding behind a gumtree”.

Labour voters are more agreeable and emotionally stable but far less open to new experiences than the average green voter. Not surprisingly, within the green movement, they tend to prefer consensus in internal decision-making but are rather uncompromising and self-righteous in their policy demands. Labour parties in Australia prefer to avoid coalitions with the Greens now because of bad experiences with their uncompromising nature in previous alliances.

As greens are more likely to get upset and are far less conscientious than others on the political spectrum, maybe they are happy to be a political movement rather than a party of government?

To be a party of government requires compromise, a willingness to appeal to the average voter, and to adopt policies because they are wedge issues rather than because they are principled stands. The Labour Party wants to govern; Greens want to make a point.

Third term governments are an ugly sight because they are unlikely to be a re-elected. Labour governments in the throes of inevitable electoral defeat are very opportunistic about changing policies to have one last roll the dice to cling to office. This is something greens are much less likely to countenance. They prefer defeat over compromise.