The visit of the royal trio Duke and Duchess of Cambridge plus Prince George may have whet the appetite of the Kiwis these days, but it should not be mistaken for a fact the fascination will go long term. A poll released on Monday said Kiwis don't want William as king and prefer a homegrown to become head of state.

A poll released by New Zealand Republic, a body seeking a New Zealand head of state, showed that William might indeed become king but not of New Zealand. The poll that included 1,038 people showed 44 per cent per cent of Kiwis prefer the next head of state to be a Kiwi, whether elected or appointed. This compared to 46 per cent who want a monarch.

The poll noted that a whopping 66 per cent of those in the 18- to 30-year-old age bracket wanted a homegrown head of state to replace the 87-year-old Queen Elizabeth who just celebrated her Diamond Jubilee.

The young royal family of Prince William and Kate Middleton will be travelling throughout New Zealand and Australia in the next three weeks.

Savage, New Zealand Republic's campaign chairman, said none of the older nor younger royals are New Zealanders and therefore are illegible to lead New Zealand.

"This issue is actually not about the popularity of the royal family. The issue is about the right of New Zealanders to choose the head of state," Savage said.

"Prince William is welcome to immigrate to New Zealand and live here and become a New Zealand citizen. When he does that he is eligible to be head of state."

The visit of two future kings and a future queen of Britain will cost New Zealand taxpayers an estimated £500,000.

The emotion of having that right to assert New Zealand's unique and distinct personality has actually started and accelerated with the goal to change the flag's design.

Spearheaded by no other than Prime Minister John Key, he wants to remove the Union Jack from the existing national flag design and put an elfin silver fern to the modernised New Zealand flag.

Supporters said it's been 70 years that New Zealand declared independence from Britain. To change the design, most specifically sever any symbols of colonial rule from the nation's flag, is long overdue.

Mr Key during a press conference on Monday also stressed that the move to become a republic "was inevitable ... it would happen and I tend to think in my heart of hearts it probably is inevitable it will happen."

Sir Don McKinnon, the former Commonwealth Secretary General, likewise sees the same thing. "I'm quite certain the Royal Family understands that completely,'' he said.

The thing is, not only New Zealand wants to pursue the case.

"I can tell you now that one Caribbean publicly, and three Caribbean, privately are probably going to give up that relationship with the monarchy when the Queen dies," he said.

"So it is a diminishing group of countries, and the important thing is for us to openly and candidly debate the issue.''