Hello: Prince William and Kate Middleton caught at the bar on a wild date night

Prince William and Duchess Kate let their hair down last week on a family holiday. The pair took all three of their children for some time away.

According to Hello, they joined Kate’s parents for their annual Mustique getaway. Reports state that William and Kate appeared to be enjoying themselves during a date night.

Prince William, 36, and Duchess Kate, 36, were spotted on a rare night out at Mustique’s famous Basil's Bar. The theme of the event was a Splash of Gold.

The party was also attended by Mick Jagger and his daughter Jade. Fellow patrons revealed that William and Kate attended "on the early side" of the party and looked to be having a great time.

For more on this story go to our Twitter account @amomama_usa. Insider’s also shared that the couple looked "island chic."

William wore a Pinkhouse Mustique shirt to support the local brand. "They were there for the cocktails segment and kept it rather classy," sources said.

The couple is good friends with legendary barman Basil Charles of Basil's Bar. In 2011, he set up a pop-up bar at The Goring hotel in London, where Kate stayed the night before her wedding.

William and Kate have been enjoying their vacation on the private Caribbean island for the past couple of weeks. It’s been reported that they joined Kate's parents Carole and Michael Middleton on the Middletons' annual break.

This is officially the Cambridges' first holiday as a family of five. Prince Louis, who was born in April, joined his big brother Prince George, 5, and Princess Charlotte, 3, in Mustique.

The Royals first visited Mustique in 2008 and have been returning ever since. The private and exclusive island allows William and Kate the opportunity to blend in with other tourists.

A no-fly zone enforced over Mustique gave the family the discretion of other guests. This meant the Royals were able to truly relax and let their hair down.

On previous trips, the couple has played tennis, gone snorkeling, scuba diving, and enjoyed cocktails at the five-star Cotton House resort.

Do you want to know more about their love story? Watch this emotional video!