Michael Cullen still regards himself as somewhat of a monarchist, but accepts that there is inevitability about New Zealand eventually becoming a republic.
Addressing the 'Reconstituting the Constitution' conference in Parliament today, the former Deputy Prime Minister said he had been misrepresented in the lead up to the conference; he was neither an ardent monarchist, nor a converted republican, as media reported at the weekend.
Though there was still majority public support to retain the monarchy, he said there "is a certain level of inevitability about a drift towards a republic".
He outlined a proposal for a majority of Parliament to elect the Head of State, rather than the present practice of having the Government select one.
As the Government has to think about the next Governor-General soon, this change could happen in the next year and would not require a law change.
After the new Governor-General is selected, Parliament could pass a law enshrining the new process, and declaring the Governor-General the new Head of State when Queen Elizabeth II dies.
The question would then remain as to whether Parliament or the public would select future heads of state.
Dr Cullen said the Governor-General was at present a ceremonial role, and as long as it stayed that way he thought electing one by a super majority of Parliament would be appropriate.
"If I was a royalist - as I have been reported as being - it might be that Parliament might choose a certain person offshore. There is nothing to prevent that. I think it's most unlikely, but it's theoretically possible."
This gradual change with many years to sink in would not scare the horses as much as a one-step change, he said.
If the issue was not dealt with until after the Queen died, the throne would be assumed by Prince Charles and moving to a republic would mean deposing the King.
"You don't have to be a monarchist to be a traditionalist - and I'm still somewhat both of those - to feel a slight queasiness around the notion of deposition of the Head of State," Dr Cullen said.
He showed his royalist leanings by criticising some of the arguments for becoming a republic as "extraordinarily weak".
"The United Kingdom is not a major threat to our cultural or economic independence. To get rid of the Queen will have absolutely no impact on those issues of national or cultural identity and independence."
He also argued that the issue of how to elect the Head of State should be separate from all other constitutional reform issues, such as allowing the Supreme Court to strike down legislation it deemed inappropriate.
"And I will die in every ditch I can find to prevent that from happening," added Dr Cullen.
The biggest problem of becoming a republic was how to deal with the Treaty of Waitangi, he said.
"Many Maori still have a deep feeling that somehow the existence of the monarchy is a protection of Treaty rights.
"The way that issue can be resolved could result in immense political difficulties."
Referring to Prime Minister John Key's dealings with Tuhoe over the Urewera National Park, Dr Cullen said: "You might call it a sort of Urewera National Park moment in our history and that can be quite destructive of where we want to get to as a country."
Earlier the conference heard from Dean Knight, a Victoria University law lecturer and supporter of "soft republicanism", who said that having a Queen made New Zealand's Head of State "hereditary, discriminatory and foreign".
"We are already a de facto republic."