As Kate chatted to the archbishop while holding Louis, she could be heard describing her sleeping son as "very relaxed and peaceful".
"There she is again sticking out her tongue just like uncle Harry", one woman joked.
Prince Louis' final godfather is Guy Pelley, who runs Tonteria, a London nightclub that used to be one of Prince Harry's favorite places to party. Take the christening of little brother Prince Louis, where she caught attention for an adorable new hairstyle.
Police officers with guns guarded the entrances to the palace while barricades were set up on streets outside to keep the crowds from spilling onto the street.
In 2015, his sister Princess Charlotte was christened at St. Mary Magdalene Church in Sandringham, a royal estate near England's eastern coast. Some were under the mistaken impression a walkabout was going to happen, but others pinned their hopes on something spontaneous.
The young prince, watched on by his older brother George, four, and sister Charlotte, three, was baptised using water from the River Jordan. The van Cutsems are close with the royal family and even once lived at Anmer Hall, which is now William and Kate's home in Norfolk.
The six godparents, who also attended with their spouses, are all friends or family of William and Kate.