LONDON — The third child of Prince William and wife Kate, Prince Louis, was christened Monday at a royal chapel in London. Grandparents Queen Elizabeth II and her husband Prince Philip did not attend, though Buckingham Palace made it clear their absence had nothing to do with health reasons. Instead, palace officials said the decision was made "some time ago." The queen has a busy week, traveling back from Norfolk on Monday, preparing for celebrations marking the centenary of the RAF on Tuesday and President Trump's visit to Windsor on Friday.

The service for Prince Louis was attended by guests including Prince Charles and his wife Camilla, and newlyweds Prince Harry and Meghan.

Louis's siblings Prince George, 4, and Princess Charlotte, 3, also joined their family at The Chapel Royal in St. James's Palace.

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Kate's parents and siblings were also there, including her sister Pippa Middleton, who is pregnant.

Louis was dressed in a cream, frilly lace royal christening gown — a replica of the intricate robe made for Queen Victoria's eldest daughter in 1841.

Kate, Duchess of Cambridge carries Prince Louis as they arrive for his christening service at the Chapel Royal, St James's Palace, London, Monday, July 9, 2018. Dominic Lipinski / AP

William and Kate chose two hymns for the service: "O Jesus, I Have Promised" and "Lord of All Hopefulness."

The Archbishop of Canterbury Justin Welby welcomed the royals at the entrance to the chapel.

As Kate chatted to the archbishop while holding Louis, she could be heard describing her sleeping son as "very relaxed and peaceful."

The duchess added, with a smile: "I hope he stays like this."

The royal couple also named six close friends and family members to be godparents to Prince Louis, who was born in April.

William and Kate, the Duke and Duchess of Cambridge, announced that they will host guests at a private tea at Clarence House and service christening cake from a tier taken from their wedding cake.