Australians are taking a natural interest in our flag debate. It raises a question for them that has become a recurring topic across the Tasman.
So it will be here if Australia holds another referendum on replacing the monarchy with its own head of state.
That possibility became a little stronger in the lead-up to Australia Day yesterday, when all state premiers bar one signed a declaration of support for an Australian head of state.
The one hold-out said he supported the move but not yet.
Since Prime Minister Malcolm Turnbull and Federal Opposition Leader Bill Shorten are both on record as republicans, the response to the declaration circulated by the Australian Republican Movement allowed its chairman to declare all the country's political leaders supported the move.
Not so long ago something similar could have been said here. John Key believed it "inevitable" New Zealand would become a republic, though he was not about to force the issue. Labour leaders have taken the same view.
But the Prime Minister now believes it is unlikely to happen in his lifetime, thanks to the popularity of the younger royals. He is usually in touch with public opinion and this is probably no exception. But if Australia takes this constitutional step, public opinion in this country could start to move.
The two countries exert a subtle gravitational pull on each other. We draw more comfort from the larger neighbour than we like to admit, and Australia does not like to think it lags behind New Zealand in any respect. It is hard to see the Australians keeping a flag with the Union Jack if we drop it from ours.
Many would say Australia is approaching these issues in the right order. A flag change would naturally follow a constitutional change.
But our flag debate has probably helped the cause of republicanism in Australia, which received added support yesterday from the country's former army head, David Morrison, as he accepted the accolade Australian of the Year to mark the country's national day.
It is more than 15 years since Australia held a referendum on changing its head of state. Its debate at that time became a three-sided issue, in which republican supporters were divided over the method of appointing a head of state.
Some wanted the position filled by direct election, others by a vote of Parliament.
Direct elections would make the head of state a more powerful figure with an independent political mandate; selection by Parliament would produce a position more like Governor General, a figurehead who would avoid contentious politics.
The declaration signed by Australian state premiers this week proposes simply replacing the Queen with an Australian head of state.
That sounds like the less radical option. It could be done by appointing a President exactly as the Governor General is chosen now, but without reference to the Queen.
This would make no practical difference to the way Australia - or, if adopted here, New Zealand - is governed, except the head of state would be in the state. It makes sense, and it could yet happen sooner than we think.