"The English names North and South Island are not official," says Don Grantz, chair of the NZ Geographic Board. "They had appeared in maps for a long time, but were not official."Let's this this absolutely clear. New Zealanders have never put much stock in paperwork. Everything from the Treaty of Waitangi and Gibbon Wakefield's dodgy torts onwards, NZers have put more stock in a person's word than their lawyers. Naive buggers, aren't we?
It took forty years before the New Zealand flag was officially recognised as the New Zealand flag. Inasmuch as the Silver Fern is our defacto second flag unofficially, or the fact that many Kiwis have their favourite national bird which is not the Kiwi. I'm a Tui. A mate of mine's a Kea. Another's a morepork. And everyone knows a keruru or two.
So the officials can call the isalnds whatever they like. The widely accepted English and Maori names are thus: North Island / Te Ika a Maui (a Tia), South Island / The Wai Pounamu. That said, I'd happily back calling the top one Heartland and the bottom one Mainland. The cheesemakers won't mind.