The Duke and Duchess of Cambridge have welcomed their third child in the world on St George's Day.
The birth certificate of Prince Louis has been made public after it was signed by proud father the Duke of Cambridge.
The document gives the full name of the latest member of the royal family as His Royal Highness Prince Louis Arthur Charles of Cambridge.
And amid the details arethe incredible job titles of the little prince's parents, known to most as the Duke and Duchess of Cambridge or, less formally, William and Kate.
Under the header "Father", William's full name reads: "His Royal Highness Prince William Arthur Philip Louis Duke of Cambridge while his "Mother" is Catherine Elizabeth Her Royal Highness The Duchess of Cambridge. Lengthy and impressive, what's also got us commoners dazzled are their job titles:
"Prince of the United Kingdom" and "Princess of the United Kingdom". If that's not a fancy job title we don't know what is.
William and Kate's third child was born at the private maternity unit of St Mary's Hospital, Paddington on Monday April 23 at 11.01am, weighing 8lbs 7oz.
The Duke, who is taking a period off following the birth of his son, signed the birth certificate earlier on Tuesday at Kensington Palace with current Westminster registrar Patricia Gordon.
The official birth register entry of Prince Louis Arthur Charles of Cambridge.
Although the birth certificate may seem a formality, it can be a stressful job as found by previous Westminster deputy registrar Alison Cathcart who revealed she received death threats over her 'messy handwriting' on Prince George's form in 2013.
Louis' document has been typed up which may have been an attempt to avoid a similar situation.
Louis' document listed the date and place of his birth and also gave the full name of his father and mother.
Normally, parents have to attend a register office within 42 days of a child being born but in this case the deputy registrar went to Kensington Palace.
Westminster City Council Registrar, Patricia Gordon, said: "It has been a great honour to register, and formally welcome the latest addition to the Royal Family, Prince Louis Arthur Charles.
"This follows a long history of Westminster City Council registering royal births, including Prince Louis' siblings Prince George and Princess Charlotte."
But Ms Cathcart found it a very different experience in 2013, after admitting she became 'flustered' when writing on the document while sitting next to Prince William at Kensington Palace.
In a 2014 interview with the Daily Mail, she said: "I got death threats. One person said their cat had better handwriting, someone called for me to be fired and someone even said I was illiterate."
She added: "Let's just say I had to have more than one attempt. What can I say? It was a very hot day and I was flustered and trying to fill this thing in with Prince William sitting beside me."
But the experience did not put her off entirely, as she described it as the 'highlight' of her career and returned to the palace two years later to write Charlotte's certificate - again by hand.
As reported by Mail Online, Louis' name serves as a poignant tribute to Prince Charles' beloved great-uncle, mentor and 'honorary grandfather', Lord Mountbatten, who was killed in 1979 when the IRA placed a bomb in his fishing boat.
Prince Louis' name was officially revealed last Friday after fans and bookmakers waited five days for confirmation, with many other names being touted as contenders including Albert and Alexander.
It comes ahead of Princess Charlotte celebrating her third birthday on Wednesday.
The royal youngster, who is getting used to being a big sister to Prince Louis, turns three just nine days after the arrival of her baby brother.
Prince Louis of Cambridge. Photo / Getty Images
Confident Charlotte delighted royal fans by waving and leading her father the Duke of Cambridge up the steps of the Lindo Wing when she was taken to meet her new sibling for the first time last week.
The princess, who is fourth in line to the throne, is now the Cambridges' middle child.
The past year saw another big change for Charlotte when she started nursery school. She attends Willcocks Nursery School, close to her Kensington Palace home.
Charlotte is expected to take a starring role as flower girl or bridesmaid when her uncle Prince Harry marries Meghan Markle in just over two weeks' time.
She has already been a bridesmaid for aunt Pippa Middleton, who wed last May.
The princess has a reputation for being feisty compared to her older brother Prince George.
