The newborn is guaranteed to be monarch of the world's most high-profile royal family regardless of whether it's a boy or a girl as a result of new succession laws.
And for the first time in more than 100 years the next three generations to wear the crown will all be alive at the same time.
Britain is getting ready to go bonkers over the Duke and Duchess of Cambridge's baby.
Film crews and photographers staked out their patch of footpath outside the private Lindo Wing of St Mary's Hospital in Paddington at the beginning of July - a fortnight before Kate's reported due date.
Renowned royal historian Hugo Vickers says every time he looks at his mobile phone someone is wanting to ask him about the impending birth.
"There is a huge amount of interest," he told NZ Newswire.
"It's partly because whether we like it or not we are approaching the end of the present Queen's reign.
"To have another generation of the House of Windsor and a baby that will one day be King or Queen is of course terribly interesting to all of us."
Royal commentator Richard Fitzwilliams says there's no question that William and Kate are the world's most glamorous royal couple.
That's why the world is about to witness "a kind of frenzy", he said.
The rise and rise of social media means news of the birth will travel faster and further than ever before.
People won't be personally involved like they were when watching the couple's wedding in 2011 or last year's Diamond Jubilee celebrations.
But they'll still feel part of it because the royal family "is a symbol of national unity", Mr Fitzwilliams argues.
"This is an event where a large number of people will get a lot of pleasure vicariously, reading about it, seeing the photographs and hearing the news about the baby."
New Zealanders may not have to wait too long to see the famous infant for themselves.
Prince William was just nine months old when first taken on a trip Down Under by Prince Charles and Princess Diana.
Mr Fitzwilliams thinks the new baby will further New Zealand interest in the royal family following the 2011 revival attributed to William and Kate's wedding.
"Three generations of succession to the throne will be alive at the same time," he said of the birth.
"Australia and New Zealand are rather proud to be part of what is undoubtedly something historic."
While succession laws have been changed to ensure the baby becomes monarch regardless of gender, royal historian Anna Whitelock points out William and Kate's child won't wear the crown for a long time.
"If the Queen lives until the same age as her mother she'd be on the throne until 2027," Dr Whitelock told NZ Newswire.
"Charles would be 80 and then you've got William to inherit.
"So we are talking about this (potential) daughter being way down the line in terms of inheritance."
Indeed the royal baby could be the first monarch of the 22nd century.
Dr Whitelock argues having three generations of direct heirs alive at the same time "underpins a sense of stability in the monarchy".
But the royal baby will also help make the British royal family more modern.
Dr Whitelock notes there are mixed feelings about Charles and Camilla inheriting the throne.
"Some of that anxiety or disquiet about the monarchy will be alleviated to some extent by this birth," she said.
While the British - and the rest of the world - may be about to go bonkers the frenzy won't last too long.
Dr Whitelock says there's not going to be much to see once the announcement has been made and William, Kate and the baby have posed on the steps of St Mary's.
"Although royal pundits are very good at talking in a vacuum, after a while there will not be much more to say," the Royal Holloway University academic said.
"We'll be in a bit of frenzied excitement for a couple of days ... but then it will burn itself out."