Prince William, Kate Middleton, Hit Night Club with Pippa Middleton [PHOTOS]

The Duke and Duchess of Cambridge made a relaxing detour to a nightclub to meet Pippa Middleton after attending separate responsibilities.

Just because Prince William and Kate Middleton have a ton of duties and appearances lined-up in their daily itineraries, it doesn't mean they don't make time to go partying in clubs. It seems like a rare instance to spot the Royal Couple out at night these days, but last night, the pair was seen in LouLou's, a private members-only club in London.

Before heading to the club, the couple had separate appearances. Prince William attended his former nanny's funeral while his wife, Kate, was busy charming crowds in the North East. After being reunited in the evening, the two decided to spend some down time with close friends and family at the swanky club.

The high-profile pair was said to be ushered in through a private entrance to avoid unnecessary attention. After all, the two are quite known to be the practical couple. The Duke and Duchess arrived at around ten in the evening, and left two hours later.

"Nobody knew they were coming and then at 10pm they were swept in through a back door. They stayed for about couple of hours." said a source to MailOnline.

The Duchess kept her simplicity and elegance by wearing a black coat over a simple dress and heels, while the Duke looked dashing in a white shirt and a suit jacket. Pippa Middleton, who met her older sister and brother-in-law in the club, stunned in a red leopard print number and her favorite ankle-high boots.

Pippa, who's embarking on a solo US tour later this month, will finally release her party-planning book entitled 'Celebrate.'

The Royal pair also spent time with Princess Eugenie, William's cousin, and Eugenie's boyfriend, Jack Brooksbank.