The Duke and Duchess of Sussex discussed moving to New Zealand during a 2018 visit, according to the Queen's representative in the country, more than a year before they stepped back from royal duties and moved to the US.

Governor-general Dame Patsy Reddy also told the Associated Press in an interview that the British monarch should remain as New Zealand's head of state, and described the hand-typed letters she sends to the Queen.

Dame Patsy, 67, will leave her largely ceremonial role representing the Queen in New Zealand in October after a five-year term.

A lawyer who was given honoured for services to arts and business, she officially signs bills into law, presides over public ceremonies and tours the country, meeting various groups including Indigenous Maori.

Harry and Meghan visited New Zealand in 2018 at the end of a hectic 16-day royal tour of the South Pacific, and Dame Patsy recalled the couple as being tired.

"I remember they'd just been down to the Abel Tasman National Park when we sat down and had a drink, and they said that they could imagine living in a place like this and wondered whether we thought it would be theoretically possible. Even possible for them to have a place in New Zealand," she said.

"Of course, we said, 'Sure. It would be fine'. There are lots of opportunities to live in New Zealand, but that would be something that they'd have to explore.

"They were looking at how they might raise their family. And obviously they've made some decisions since."

Dame Patsy said she did not view it as a formal request for assistance but more of an informal discussion about the couple's hopes for the future. She said they seemed impressed with access to the outdoors and their interactions with New Zealanders.

The discussion shows the couple were considering options outside Britain less than six months after they married and well before their eventual move to the US.

During a widely watched interview with Oprah Winfrey earlier this year, Harry and Meghan said they had offered to take a step back from royal life in a Commonwealth country such as South Africa or New Zealand.

Dame Patsy said she watched the interview but did not want to comment on internal royal family business.

"I thought they were a lovely couple and I hope they've got a great future where they are," she said.

She added that she regularly expresses her confidential views of what is happening in New Zealand to the Queen, such as the nation's response to the pandemic. She said the communication "is quite touchingly old-fashioned, by letter".

"She has told me on the times that I've seen her that she finds it interesting to have a personal perspective on what's happening," Dame Patsy said.

"As she says, 'I like to know what's happening between the lines'."

Many people in New Zealand believe the country should become an independent republic but Dame Patsy said she believes the queen should remain the head of state because the arrangement works and has strong historical links.

She said New Zealand has a special connection to the monarchy because its founding document, the Treaty of Waitangi, was signed by Maori and a representative of Queen Victoria.

Asked about a future scenario in which a monarch might turn out to be dictatorial or autocratic, Dame Patsy said the same scenario with an elected president would be likely to be worse.

"We've seen how that doesn't work in other countries in the world," she said. "But actually, because the monarch is much more of a theoretical construct, a figurehead rather than an actual ruler, I think it gives us a measure of safety, constitutional safety."

She said she agreed with Prime Minister Jacinda Ardern's assessment that there was currently little appetite among New Zealanders for a constitutional change, and that people were concerned about more pressing issues like climate change, inequality and the pandemic.

She said the royal family had been great role models during the pandemic, using the internet and social media to great effect and abiding to the rules imposed by the UK Government.

"So we saw tragically the funeral of Prince Philip, where they could only have 30 mourners," Dame Patsy said. "But there was no question that there'd be any kind of dispensation, even from the requirements for isolation, when, for example, Prince Harry came back to that funeral."

She pushed back at the negative portrayal of the prince of Wales, saying she thought he would be a good monarch.

"I've been enormously impressed with the breadth of his knowledge, the depth of his well-considered perceptions on a range of subjects," she said. "From urban planning to the environment, to the impact of religions on the world."