Britain's Prince William and his wife Kate
Britain's Prince William and his wife Kate leave after attending the Christmas Day service at church in Sandringham, eastern England, December 25, 2015. Reuters/Peter Nicholls

Kate Middleton wore a green Sportsmax coat for the traditional Christmas Day church service at St Mary Magdalene church in the Sandringham estate, Queen Elizabeth II’s country retreat in Norfolk. Within a few hours of the Duchess of Cambridge being spotted in the outfit, it sold out on the Sportmax site. She wore a calf-length green coat by Sportmax which was belted on the waist with a black belt.

Due to the "Kate Effect", the coat has sold out everywhere including Farfetch. Kate looked beautiful in a Great Plains patterned dress under the belted coat. The coat, which was cinched at the waist with a black belt, showed off her svelte frame. She accessorized with a classic diamond brooch, which featured oak leaf and acorn.

She wore Lock and Co fascinator, black Aquatalia boots and carried a Mulberry clutch bag. She also wore a pair of drop earrings. The 33-year-old royal looked conservative chic in her church attire. Her brunette tresses were styled into an elegant chignon.

Kate’s day make-up look consisted of her signature smoky eyes and some brown lipstick. Meanwhile, Prince William opted for a black long coat and white shirt with a red and white tie. He carried an umbrella to shield his wife and himself from the rain.

Others members of the British royal family, who attended the service, included the Queen Elizabeth II, Prince Charles, the Duchess of Cornwall, Prince Harry, Princess Beatrice, Princess Eugenie and Princess Anne. Prince George and Princess Charlotte were left at home, despite speculation by a section of the media that George would be in attendance.

Elizabeth stole the show at the church service with her festive red coat. The coat featured gray fur trim on the sleeves and neck. The 89-year-old monarch carried an umbrella to protect herself from the downpour. The transparent umbrella had red trim on the edge. She arrived at the church in a Bentley along with her daughter-in-law Sophie Wessex.

Kate and William went to Anmer Hall, their countryside home in Norfolk after the service. The couple hosted Kate’s parents and siblings for Christmas lunch. This is the first time that the couple spent Christmas as a family-of-four.