Kate Middleton and Prince William on Jan. 10. Credit: Max Mumby/Indigo/Getty Images

A big morning after a big birthday night! Duchess Kate attended a morning service at the St. Mary Magdalene Church in Sandringham, England, on Sunday, January 10, a day after celebrating her 34th birthday.

An insider tells Us Weekly that the royal mom of two made the surprise appearance alongside her parents, Michael and Carole Middleton, sister Pippa and brother James, who had all traveled to Sandringham to celebrate her birthday.   

The duchess wore a black turtleneck, tweed blazer and skirt by Michael Kors, and accessorized with a black hat, black Aquatalia boots and clutch. After services, she and husband Prince William, 33, attended a ceremony marking the 100th anniversary of the Gallipoli campaign during World War I.

The couple also joined Queen Elizabeth II and the Duke of Edinburgh at a wreath-laying service held at a nearby war memorial on the queen's Sandringham estate.

Kate celebrated her birthday on Saturday, January 9, with a private, simple celebration at Anmer Hall, the country home that she and William recently renovated on the Sandringham estate in Norfolk, England. 

A source told Us on Saturday that the birthday girl wanted "a low-key celebration," adding, “Kate doesn’t like to make a fuss.”

Kate — who is mom of Prince George, 3, and Princess Charlotte, 8 months — has a busy year ahead of her.

She and William are heading to India and Bhutan together for the first time.

“TRHs look forward to following in the footsteps of previous generations of their family with their upcoming tours,” the official Twitter account for Kensington Palace tweeted on Friday, January 8, alongside an image of Princess Diana, Prince Charles and the queen.

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