The Duke and Duchess of Sussex have named their baby son Archie Harrison Mountbatten-Windsor.
A surprise choice, Archie was not among the bookmakers' favourites of Alexander, Arthur and Albert.
"I don't think anyone of us saw either of these names coming," says Joe Little, managing editor of Majesty royal magazine.
As far as he is aware, Archie does not have any British royal connotations - and Harrison too is a totally new name for the Royal Family.
Archie means "genuine", "bold" or "brave" - and is more popular in Britain than the US. It was originally a shortened form of Archibald but is now often used as a name on its own.
It was the 18th most-popular boy's name in England and Wales in 2017, with 2,803 baby boys called Archie that year, and has been in the top 50 consistently since 2003.
Harrison is slightly more popular than Archie in the US - although it's still more common in the UK, where it was ranked the 34th most-popular boy's name in 2017.
And, rather fittingly, Harrison - a name which was originally used as a surname - means "son of Harry".
Mr Little said: "It may well be it's a name that Meghan is familiar with and again that's why they are using it," he said.
"Archie has a British feel to it, whereas Harrison is more of an American name. The first Harrison that springs to mind is Harrison Ford.
"They have wanted to do something a little bit different, and they have done."
Some had wondered whether either of the new baby's grandfathers' or great-grandfathers' names might appear as a middle name - either Philip or Charles on the royal side, or Thomas on Meghan's.
"Again, it's down to the parents," said Mr Little. "It's their choice."
Harry and Meghan have also chosen not to use a courtesy title for their new son.
As the first-born son of a duke, Archie could have assumed the title of Earl of Dumbarton but he will instead simply be known as Master Archie.
Royal commentator Richard Fitzwilliams said the individuality shown by Harry and Meghan in their choice of non-traditionally royal names was "marvellous" and would "rejuvenate the monarchy".
"It's a unique choice, by a unique couple who are doing things in a unique way," he said, adding: "We are talking about brand Sussex, which is an international brand."
It is not the first time that a British royal baby has been given a name which is not traditionally royal. The name given to the Queen's first granddaughter - Zara Phillips - "caused quite a sensation" when it was unveiled, said Mr Little.
Famous Archies include Archie Panjabi, who starred in The Good Wife; Archie Andrews in Archie comics in America and also the Netflix show Riverdale; and Archie Mitchell, a villain in the BBC soap EastEnders.
Family history website Ancestry said it expects the name Archie to become even more popular, having analysed the impact of other royal baby names. It said George and Charlotte both jumped up the rankings in the UK, as did William and Harry.
Mountbatten-Windsor is the surname which was created in 1960, combining the surnames of the Queen and Prince Philip when they married. The double-barrelled name was a concession to the Duke of Edinburgh, who was said to have complained that his children would not bear his name.
The three children of the Duke and Duchess of Cambridge all have Cambridge on their birth certificates.
Royal author Penny Junor said she thinks the Duke of Edinburgh would be "absolutely thrilled" with his surname being used.
"Prince Philip was never allowed to call his children by his own surname," she said. "I think that's a really nice tribute to Harry's grandfather."