Prince Louis, the third child of Britain's Prince William and wife Kate, will be christened at a small, private ceremony overseen by the Archbishop of Canterbury later on Monday, but Queen Elizabeth will not be there, his father's office said.
Some royal fans had expected to see Meghan, the Duchess of Sussex among the godparents, after she married William's younger brother, Prince Harry, in May, but she has not been included among the six.
Her hat, by Jane Taylor, was a headband-style piece with floral accents, and completed the elegant look.
Prince William, Kate Middleton, Prince Harry, and Meghan celebrated the RAFs 100th anniversary. As she and her family left the chapel where Prince Louis had been baptized and began to make their way to a post-christening reception party, she told the phalanx of photographers "you're not coming" or perhaps "he's not coming". The queen, dressed in a royal blue outfit with turquoise edging, later hosted a ceremony to present the RAF with a new Queen's Colour, at which she recognised the service's work.
Meghan and Harry, who tied the knot at St George's Chapel nearly two months ago, looked completely in love and held hands as they arrived at the Chapel Royal, at St James' Palace, alongside the Cambridges, the Prince of Wales and the Duchess of Cornwall. She's been playing it safe by keeping her looks simple.
She shared a memorable laugh with the Prince of Wales and Duchess of Cornwall at a Buckingham Palace garden party days after her wedding.
"Bringing together that big parade, the new colour and the flypast - this is going to be a tremendous day, and it is about commemorating all of our history, and it is about celebrating what we do today", he said.