The Queen is 86. She has been part of the furniture for so long that her latest waxwork image at Madame Tussauds in London is the 22nd version of the monarch.
The Queen is many things - a mother, grandmother, and great-grandmother to an often-dysfunctional family, the head of Britain's armed forces with the right to declare war and peace, a taxpayer - since 1993 - and, for six decades, the wife of a 90-year-old still given to off-colour remarks. (Last month, on a royal walkabout in south London, as part of Britain's jubilee celebrations, the gimlet-eyed Duke of Edinburgh passed Hannah Jackson, a tall blonde wearing a red dress with a full-length zipper. "I would get arrested if I unzipped that dress," muttered the Duke to a nearby policeman.)
For all the Queen has accomplished, even she cannot last forever. At some point her reign will end and most likely Prince Charles, her eldest son, will succeed to the throne. He would become, with a few constitutional tweaks, King of New Zealand.
Or he may not. This year's jubilee, the Queen's age, the tepid ratings for Charles - all suggest that sooner or later the question of New Zealand having its own head of state will be back on the public agenda.
Beyond that hovers a much broader constitutional landscape: the fate of reserve powers - the uncertain authority of a governor-general to sack an elected government - the future of the flag and national anthem, the status of the Treaty of Waitangi, the prospect of a written constitution.
Efforts to crank up even the barest of these reforms - a home-grown head of state - have struggled in New Zealand. A push during the last Parliament by long-time republican and former Green MP Keith Locke to cut the strings to Buckingham Palace fell at the first hurdle.
Two years on, former Prime Minister Jim Bolger repeats his assertion that the time has come at least for our own head of state. The son of Irish immigrant parents, Bolger was New Zealand's most republican premier.
He once spent 45 minutes in a private audience with the Queen explaining why he believed New Zealand becoming a republic was "inevitable". (He jokes that he emerged with his head still on his shoulders.)
Protocol prevents him disclosing what the Queen thought of the republic idea, though Sir Don McKinnon, for eight years head of the Commonwealth Secretariat in London and, before that, Bolger's deputy in Government, says the Queen would offer her best wishes to any country determined to go its own way.
McKinnon, who says he's had 30-plus meetings with the Queen, remains well-connected with currents in the Commonwealth. He has just completed an assignment as special Commonwealth envoy to the Maldives, the Indian Ocean republic locked in a political crisis.
Of the 16 realms in the Commonwealth - New Zealand is one - McKinnon says "quite a few are thinking that in terms of the departure of the Queen, [it] may well be the time to rethink their association with the monarchy and replacing the current head of state.
"It's not sort of alien thinking in the Commonwealth. Jamaica is the only one that has made a forceful statement saying it's time they probably moved. Most others are keeping their own counsel but the mood in many countries is that it may be the time to make a break."
Says Bolger: "I've tried to make it clear the Queen is highly respected. I think she's done a magnificent job. It's just that I think New Zealand has matured as a state to the point where we should elect our own head of state. Not a very radical thought. About 200 countries around the world do it."
During his time as Prime Minister, Bolger tried to stir republican sentiment and even suggested the year 2000 as a date when New Zealand could become a republic. Twelve years on, the country remains a constitutional monarchy with a head of state in London.
Bolger likes, as a first step, a proposal suggested by the former Labour Deputy Prime Minister Michael Cullen. A lower-case monarchist, Cullen's idea for "modest change" is for the election of a new head of state when the Queen dies or relinquishes her throne.
His new indigenous head of state would have the same powers as the Governor-General, be called something else - in te reo, the Queen is "kotuku", or white heron - and get the job on the basis of a super-majority in Parliament, or 75 per cent in favour. Cullen also has an alternative plan, with legislation clearing the way for the incumbent Governor-General to become head of state on the death of the Queen, making New Zealand a "republic-in-waiting".
But even then Cullen senses little appetite for a republican state, asserting that, though inevitable, it remains a close run thing between constitutional change and raising the age of super as to which issue New Zealand's political leadership avoids for longest.
"I think, " he adds, "the arrival of William and Kate will probably delay the date for a long time to come."
Monarchy New Zealand, which beats the drum for the current set-up, cautions that even minimal change courts danger. In a section on its website, headed "myths and mistakes", the lobby argues: "Removing a piece of our government is akin to removing a part from the engine of a car and expecting it to run properly."
Canadian Sean Palmer, the group's chairman, is not unsettled at the thought of a revived republic debate. "When people look at the brilliance behind our constitutional structure and how well it has operated for years, I think that will help to win them over. Most don't tend to think about it because the system works so well."
Palmer says young, patriotic New Zealanders support the lobby, though he declines to divulge its membership. "We're not a group of devout monarchists collecting biscuit tin lids," he remarks.
Support for a New Zealand republic waxes and wanes. Polls consolidated by the Republican Movement of Aotearoa show a majority favour existing arrangements.
In 2008, a telephone survey by Curia Market Research found the country virtually split between the option of King Charles or a republic. Last year a poll by the same company found the Prince of Wales had firmed to 54 per cent, with 35 per cent preferring a republic.
Some of the shine from Prince William's Westminster Abbey wedding seems to have rubbed off on the monarchy. A UMP survey after the second-in-line to the throne exchanged vows with commoner Kate Middleton - who, with her sister Pippa, is one of Time magazine's 100 "most influential people in the world" - seemed to get a tick for the palace with 58 per cent opposed to a republic.
For republicans, the response to a second question posed by UMR was even bleaker: 52 per cent of the 750 people surveyed did not expect New Zealand to become a republic within the next 20 years. When the question was asked in 2005, a majority (58 per cent) believed the country would be a republic by 2025.
One place the republic issue might get a dust-off is in submissions to an independent panel reviewing New Zealand's constitutional arrangements. Set up as part of the coalition deal between National and the Maori Party, the panel's terms of reference do not mention the "R" word, but that should not be an obstacle when it "seeks the views of all New Zealanders" on constitutional matters.
Maori Affairs Minister Pita Sharples accepts the issue might be raised by submitters, in which case the cabinet would discuss whether it "deserves further consideration." But Sharples, who along with Bill English, is overseeing the constitutional review, doesn't want debate over a republic to distract from other matters such as the Treaty of Waitangi.
He says that for Maoridom the place of the Treaty in New Zealand's constitutional arrangements is more important than a korero about a republic. From his observations, he considers the idea of a republic is "of interest" to Maori but to his mind the Treaty takes centre-stage.
Republican advocates argue it is straightforward to accommodate the Treaty in a republic.
Dean Knight, legal adviser to the Republic Movement, a lobby pushing for constitutional change, says there are "mischievous myths circulating that the Treaty complicates a move to a republic. It doesn't.
"Legal and constitutionally, transforming to a republic does not upset or change the important Treaty relationship."
Knight, a senior Victoria University law lecturer, observes: "The constitutional reality is that the Crown's obligations under the Treaty fall on the New Zealand government of the day. That would continue under a republic."
He says ministers in the Beehive - and not the sovereign in Buckingham Palace - are responsible and accountable for upholding the State's Treaty undertakings.
Bolger concurs: "The question of honouring the Treaty or not honouring it as the case may be has been in the hands of the government of the day and not in the hands of the Royal Family in London. It is the Government of New Zealand that has the responsibility to carry forward the commitment of the Treaty.
"That's not insurmountable but it's important to have a detailed discussion with Maori leadership."
Adds Knight: "It's important, though, that iwi and hapu are reassured that nothing is lost - but they can be comforted by the fact that constitutional experts, and even monarchists, acknowledge soft republicanism does not upset the Treaty relationship."
The "soft republicanism" Knight mentions is a kind of "don't frighten the horses" approach to the change at central casting. He believes it's the right fit for New Zealanders and reflects constitutional reality.
"Our pragmatic culture favours small modest steps, not radical reform. Evolution, not revolution. And promoting the Governor-General to the top job and rebranding the Crown as the State is all that's needed constitutionally too."
The Republic Movement's masterplan involves two referenda, the first to gauge support for constitutional arrangements, followed by a binding ballot on whether to embrace a republican future or stick with the existing set-up.
Legal blogger and barrister Graeme Edgeler cautions that the simple steps approach may in fact be far from straightforward.
"We shouldn't kid ourselves," he warns. " The enormous symbolic change that a republic would encompass will see a push for more substantive change from many quarters. Any suggestion that adopting a simple transition from a British figurehead to a New Zealand one will mean we are able to sidestep the more fraught constitutional issues is misplaced.
"Some will see any move to republic, however minor the change intended, as a way to address or remove issues like the ongoing Treaty relationship, and indeed, whether it should be ongoing at all."
Even technical matters will need a lot of work, notes Edgeler.
"Someone needs to go through every piece of law we have, and amend every reference to the Crown or the Monarch, so that it makes sense."
For example, amending the Citizenship Act would require that new citizens no longer swore allegiance to the Queen, and the Sovereign's birthday - this very weekend - would be dropped from the Holidays Act. Says Edgeler: " There will be thousands of these minor changes."
He doubts the link to the monarchy will be cut any time soon. "This is the type of change we should be making only once we're sure - and if you're having trouble getting people engaged in the debate, that will be a pretty good indicator that it's not a change the public really wants."
Dean Knight, currently in London on sabbatical, says he's been struck by the gulf between Britain and New Zealand.
"King Charles is about as un-Kiwi as they come. It's not his fault, he's a born-and-bred British aristocrat. It's just plain daft expecting him to be a symbol of New Zealand. And I'm sure that if Kiwis were given the chance to choose, they would back one of their own as head of state."
