A royal birthday bash!

Kate Middleton's parents, Carole and Michael Middleton, have jetted off to the small private island of Mustique to celebrate the family matriarch's upcoming 60th birthday, according to a new report.

carole and michael middleton

Carole and Michael Middleton in July 2013.

Carole — who turns the big 6-0 on Jan. 31 — will be joined by her six-months-pregnant daughter, Kate, son-in-law, Prince William, and grandson, Prince George, among other family members and friends, for a lavish party at Villa Rocina.

"William and Kate have edited their friends so much that it's really a closed family affair, with just those who are very trusted and wealthy Mustique residents invited, and only the closest of friends from back home who have proven over the years their trustworthiness," a source told 'E! News' of the uber private party.

Related Story: Pregnant Kate Middleton Reveals She Can Feel Baby No. 2 Kicking "All The Time"!

During the celebration, guests will reportedly toast to the Duchess of Cambridge's mother with a signature cocktail, while pregnant Kate sips on a specially-made, non-alcoholic "mocktail"!

kate middleton vacation 2

The island of Mustique; Kate, William and George in April 2014. (Credits: R/R | Splash)

Oh, to be a fly on the wall of that shindig!