New Zealand was one of the first Commonwealth countries to mark the birth of the Royal baby today with a 21-gun salute.

The New Zealand Defence Force held the salute at Point Jerningham in Wellington at noon.

Troop Commander Lieutenant Michael Doughty said they received word this morning of the birth.

"I've heard that because of the late timing of her birth last night we'll likely be the first country in the world to fire a salute," he said.

About 40 members of the public turned out to watch the salute carried out by members of the 16th Field Regiment, an artillery unit based at Linton Military Camp.

Roseneath resident Holly O'Rourke, 12, said she was excited by the birth and hoped the couple would call their first-born Jack.

"They're a nice couple, I made a Facebook video of the gun salute," she said.

Her grandmother, Christina Speirs, preferred the names James or George.

"We usually watch the salutes from home because we look over Point Jerningham, but we decided to come down today," she said.

Another resident, Lou Hunt, said she had the day off work after her building needed further structural inspections after Sunday's earthquake.

"I've always wanted to see the salute live."

Lieutenant Doughty said the guns were kept at Point Jerningham permanently for salutes.

" It's historically been the location of gun salutes, because it points out into Wellington."

The royal birth had been the talk of the last few weeks, he said.

"We are pretty excited about it. It's always good to see a new baby being born."

- APNZ