Royal watchers may have recognized Prince George's outfit. It was very similar to the one worn by his father, Prince William, when he visited his newborn brother, Prince Harry, on September 16, 1984.
Only a handful of people were invited to the picturesque church on the Queen's Sandringham Estate, where the Duke and Duchess of Cambridge also have a home.
The guests included Charlotte's grandparents, great-grandparents and aunt and uncle on the Middleton side. Prince Harry would have been invited but is away in Africa.
Princess Charlotte of Cambridge
Princess Charlotte of Cambridge 13 photos
EXPAND GALLERY
First photos of Princess Charlotte with Prince George
First photos of Princess Charlotte with Prince George 4 photos
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In the past, christenings were grander affairs, but Kate and William prefer intimacy. In a break from tradition, they didn't choose members of the royal family as godparents. Instead they asked three of their oldest friends and a cousin from both sides.
William chose Laura Fellowes, a cousin from his late mother's branch of the family. This was one of several nods to Princess Diana, whose memory he tries to include in family occasions. This was also the church where Diana was christened. The official photographer was one of Diana's favorites, Mario Testino, and one of Charlotte's middle names is Diana.
Despite the informality of the day, key traditions were included if you looked closely. Charlotte wore the royal christening robe last sported by her big brother at his christening in October 2013. The ceremony was overseen by the Church of England's most senior bishop, the archbishop of Canterbury, Justin Welby. He used the lily baptismal font, which was quietly brought up from the Tower of London, where it is housed with the crown jewels. The water in the font came from even farther away -- the River Jordan.
And of course you cannot be the British royal family without drawing some attention. Aware of this, the duke and duchess invited the public to a field outside the church to share the moment. When the Cambridges emerged from the church, there was a cheer from the thousands who had gathered for what was the first public outing of this new family of four.