The youngest child of the Duke and Duchess of Cambridge is fifth in line to the British Crown after his two older siblings, his father and his grandfather the Prince of Wales.

The name of Prince William and Katherine's third child has been announced as Louis Arthur Charles.

The announcement from Kensington Palace has ignited an immediate outpouring of reaction and well-wishing online.

The new Prince's royal style will be "His Royal Highness, Prince Louis of Cambridge."

Prince Louis is widely believed to have been named for the adoptive uncle of his great-grandfather Prince Phillip, Louis of the House of Battenburg later to be renamed Mountbatten. His third Christian name, Charles is a nod to the next British Monarch, his grandfather Charles the Prince of Wales.

In a break from the traditions of the past, Prince Louis will not automatically displace his older sister Princess Charlotte in the line of succession, as the Parliamentary Succession to the Crown Act of 2013 eliminated the automatic preference for male heirs, instead favoring "absolute primogeniture" according to which the eldest child succeeds regardless of gender.