Britain's Prince William (C), Duke of Cambridge Son to Join Air Ambulance.
Prince William will be joining EAAA as a pilot very soon. Reuters

The royal visit to New Zealand by the trio family of Prince William, Kate and baby Prince George will cost taxpayers a whopping $1 million per day, no less than Prime Minister John Key announced. He was quick to defend however the "tremendous international coverage" the Kiwi country will get in exchange.

The Duke and Duchess of Cambridge, along with eight-month-old son Prince George, are set to spend nine days in New Zealand in April.

"In the end, these royal visits aren't cheap, whether it's Prince Charles and Camilla or in previous times when the Queen has come to New Zealand," Mr Key said on Firstline on Tuesday.

"But on the other side of the coin, if you look at what will happen over the course of that 10 days, New Zealand will get tremendous international coverage."

Britain's Prince William (C), Duke of Cambridge, helps with flood defences at a petrol station in Dachet, southern England, February 14, 2014. REUTERS/Paul Hackett

He said he's excited over the photos and images that will be beamed around the world by the media pack who follows William and Kate, and baby George. "You go and think about what it costs if you want to host one of those shows like Bachelorette or whatever it might be in a country like New Zealand, the Great Race [sic], you pay enormous amounts of money."

"In essence William, Kate and baby George will be promoting New Zealand."

The Cambridge's are expected to arrive on April 7 in Wellington, where they will be greeted at Government House, before spending ten days in the country. Eight of those days are packed with engagements.

Prince William and wife Catherine will visit the air force base at Whenuapai as well as four South Island and four North Island centres.

The royal Cambridge duo will mostly make day trips to various parts of the country, then return to be with Prince George in the evening, Mr Key said.