THE Duke and Duchess of Sussex have welcomed the arrival of their first child, the latest addition to the Royal family.

The arrival of a son was a surprise for proud parents Meghan and Harry, who chose not to find out their baby's sex beforehand.

American former actress Meghan had already indicated they would be delighted with either a girl or a boy.

As a first-born boy, the new addition to the Sussex family will one day succeed Harry as the Duke of Sussex.

Baby Sussex is not a prince or an HRH because George V limited titles within the royal family more than 100 years ago.

His title is expected to be Earl of Dumbarton - as the son of a duke, he is entitled to use one of Harry's lesser titles.

The Scottish title - which refers to Dumbarton on the north bank of the River Clyde, to the west of Glasgow - was given to Harry by the Queen on the morning of his wedding.

The baby's surname is expected to be Mountbatten-Windsor.

Mrs Obama said of the duke after witnessing them together in 2016: "I have to say the most precious thing, if you haven't already fallen in love with him, is to see him with his nephew."

A baby boy means Charlotte remains the only girl among the Prince of Wales's four grandchildren.

Charles now has three grandsons - George, Louis and Baby Sussex.

But the LA-born former actress may decide to draw on American culture when picking a name.

The baby will only become a prince if the Queen steps in at the last minute by issuing a Letters Patent under the Great Seal of the Realm.

If this happens, the baby will become history's first Prince of Sussex.

The previous 19th century Duke of Sussex - an eccentric son of King George III - had both his marriages deemed illegal.

His mistress, Lady Augusta Murray, was not the Duchess of Sussex and his illegitimate son was plain Master Augustus Frederick d'Este.

Lady Augusta did, however, continually refer to herself as a duchess and a princess, and staff called her son Prince Augustus and her daughter Princess Augusta.

Baby Sussex will one day be entitled to become an HRH and a prince when his grandfather Charles eventually becomes King, but he or his parents could decide to keep his current title instead.

The new baby is seventh in line to the throne.