Prince Louis is also the first male royal who will not overtake his sister in the line of succession after a reform that ends male primogeniture. The baby's full royal title is His Royal Highness Prince Louis of the United Kingdom of Great Britain and Northern Ireland, royal historian Marlene Koenig told Town & Country, but Kensington Palace announced he'll go by His Royal Highness Prince Louis of Cambridge.
On Monday, April 23rd, the Duke and the Duchess of Cambridge took to the stairs of the Lindo Wing at St Mary's Hospital in Paddington, London to officially introduce the world to their third child. "The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, Prince Harry and members of both families have been informed and are delighted with the news", Kensington Palace's Twitter feed announced shortly after the new royal's arrival.
However, while she may be within her rights to have Princess in her name, it is not her title, which can only be honoured to those who are royal by birth.
Louis is now the 71st most popular name for a baby boy in England and Wales - a long way behind George, which is in third place.
The royal couple has spent the last week getting to know the new prince and celebrating with the royal family.
"This follows a long history of Westminster City Council registering royal births, including Prince Louis" siblings Prince George and Princess Charlotte'. It's been called "a sentimental choice", though the name also appears in 4-year-old Prince George's name and babydaddy Prince William's name too-it's safe to say Mountbatten was a popular relative. Kate only adopts the title of Princess because in the United Kingdom she takes on her husband's title.
The middle name Charles is also a tribute to William's father.