Choosing this name would be a nod to the baby's great-great-great-great-great grandfather, the beloved husband of Queen Victoria. The name is also shared with St. Albertus Magnus, a 13th-century Doctor of the Church who was a scientist among many other things. He was also a diplomat, which might serve the little royal well in his future role.
Choosing to name the baby after his uncle, Prince William, would be a lovely gesture, but it's also the name of his Norman ancestor, William the Conqueror, who invaded England, bringing about radical change in medieval times. And another great William is the saint who was an English priest who traveled to Denmark to evangelize the country. He courageously admonished a Danish king to defend the Church. Luckily he survived, absolved the king of his crimes, and the two became close friends.
By choosing this option there could be another "Harry" in the family -- Prince Harry's real name is Henry. King Harold was the last crowned Anglo-Saxon king of England, whose coronation took place in Westminster Abbey in 1066, months before the Norman invasion. While there is a St. Harold, not much is known about him other than he was a child martyr in the 12th century. If the royal couple want to go back to their regal roots they could opt for the Old English version: Hereweald.
One of the most regal of names, meaning ruler, leader, or king. There haven't been many Richards in the modern royal family, but of course there is the well-known Richard Lionheart, the Christian commander who led his men on the Third Crusade. Interestingly, St. Richard, the Bishop of Chichester, is the patron saint of Sussex, so this would be a perfect choice.
Naming their son after his grandfather -- Prince Charles, the next in line to the British throne -- would be a very thoughtful choice. It is also name shared with the 17th-century king, Charles I, considered by some a saint, whose refusal to abandon his belief in the divine right of kings and his marriage to a Catholic ultimately led to English civil wars and his beheading. His son, Charles II, converted to Catholicism on his death bed.
King James II was the son of Charles I and the last Catholic monarch of England, Scotland, and Ireland. His conversion to Catholicism affected many of his decisions as king. He was eventually forced into exile by his own daughter, Mary, and her Protestant husband, William of Orange, as opponents feared the growing strength of Catholicism in the country. And of course, James is the name of two Apostles in the New Testament. So a baby James Sussex would be in great company!
This is a natural choice for a little boy who shares a birthday with the feast of the patron saint of choirboys, St. Dominic Savio. The young Dominic was exceptionally devout and hardworking and was well-versed in his faith. Meaning "Belonging to God," this name reminds us that the wee royal is truly a child of God.
Slightly more unusual, Edwin was a king in the north of England in 616, who converted to Christianity after his wife's persuasion. He was later venerated as a saint after dying in a battle at Hatfield Chase. The name steeped in history can easily be shortened to Ed or Eddie for a contemporary touch.