Sources tell Us Weekly that the royals arrived in the Grenadines midweek. The trip was planned in part to celebrate the 60th birthday of the Duchess of Cambridge's mother, Carole Middleton.
Turning the big 6-0 on Saturday, Jan. 31, Carole will be fêted in Mustique by her eldest daughter, son-in-law, grandson, husband Michael Middleton, and two younger children, Pippa, 31, and James, 27.
The Duchess, 33, and her Duke, 32, are staying in style on the private island. Insiders tell Us that the married couple and their 18-month old son are residing in a $25,000-a-week Balinese-style hilltop villa that boasts a 64-foot pool and a staff of six.
Mustique has been a popular travel destination for the royals, who are making one of their last trips as a threesome before Middleton gives birth to the second royal baby in the coming months. The gorgeous Brit announced this past September that she and Prince William are expecting their second child.
When Prince George was just 6 months old, the trio escaped to Mustique in January 2014, earning the royal tot the first stamp on his quickly filling passport. Twelve months prior, in January 2013, the Duke and Duchess took a babymoon trip to the island ahead of George's birth.
Now showing a baby bump in her always chic maternity clothes, Middleton dished on her pregnancy this week. "It's moving all the time," she said of her baby-to-be at an event in London on Monday, Jan. 19. "I can feel it kicking now."
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