THE royal baby has been named Prince Louis Arthur Charles as Kate Middleton and Prince William finally revealed the name of their son.
After four days of feverish speculation the name was announced by Kensington Palace on Twitter this morning.
The child appears to have been named after Louis Mountbatten, the much-loved uncle of Prince Philip who was killed by an IRA bomb in 1979.
His full title is His Royal Highness Prince Louis Arthur Charles of the United Kingdom of Great Britain and Northern Ireland.
But he will be known as HRH Prince Louis of Cambridge.
William and Kate's choice shocked punters, with Louis a 20/1 outsider this morning.
By also giving Louis his father's name, William has continued the tradition of handing down royal names through the generations.
The tot, born a healthy 8lbs 7oz on Monday, will join Prince George and Princess Charlotte in the next generation of the royal family.
The newborn shares the French name with his brother George, who has it as one of his middle names. Louis - which is to be pronounced with a silent "s" - is also one of William's middle names.
A ROYAL INSPIRATION: Who was Lord Louis Mountbatten?
Louis Mountbatten was Prince Charles' much-loved great uncle, who was assassinated in 1979.
Born Prince Louis of Battenburg in Windsor in 1900, he quickly became a prominent figure with the Royal Navy.
The royal served during the First and Second World Wars, later serving as the Chief of Defence.
Married to Edwina Ashley, he had two daughters.
Lord Mountbatten was murdered by the IRA aged 79, who planted a bomb on a boat at his summer home in Mullaghmore, Ireland, in August 1979.
The IRA took responsibility for the explosion, calling it an "execution".
Lord Mountbatten was Prince Charles' great uncle, with the pair having an extremely tight bond.
Prince Charles even referred to him as like the "grandfather he never had".
Prince William may have given an early hint to the names he was considering as he emerged from the Lindo Wing on Monday, after he said: "There's Arthur, there he is," as he pointed to legendary Sun photographer Arthur Edwards.
Louis - a name of French origin meaning renowned warrior - was only the bookmakers' 10th top choice, with Albert and Arthur the favourites this morning.
The name is thought to be inspired by Earl Mountbatten of Burma, a prestigious naval officer who Prince Charles described as "the grandfather I never had".
The moniker has been given to 18 kings of France - and musicians as diverse as Tomlinson and Armstrong.
William appears to be paying tribute to both his parents in choosing Charles as one of Louis' middle names - matching the decision to give his daughter Charlotte the middle name of Diana.
The Duke and Duchess now have three children under the age of five - something William referenced outside the hospital, joking: "Thrice the worry now!"
Prince William said his two eldest - aged two and four - were "delighted" with their new baby brother.
The name revelation comes after four days of packed royal engagements, during which Harry asked William to be his best man at his wedding with Meghan Markle next month.
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Wearing a red bespoke Jenny Packham dress, Gianvito Rossi nude heels and earrings loaned by the Queen, she beamed as she carried her new son.
Prince Charles has also shown himself ecstatic over the birth of his latest grandson, saying in a statement: "We are both so pleased at the news.
"It is a great joy to have another grandchild, the only trouble is I don't know how I am going to keep up with them."
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