When Australia's Prime Minister Scott Morrison met his New Zealand counterpart Jacinda Ardern in the idyllic surroundings of New Zealand's Queenstown earlier this week, both leaders were keen to say how close the relationship is between their two countries.

Mr Morrison spoke of the two countries as a "family", and that is hardly an exaggeration. There are probably no two countries in the world that are more alike in so many aspects of their national life as these two former outposts of the British Empire in the South Pacific.