Prince William, Kate and Prince Harry Attend Royal Foundation Dinner

The Duke and Duchess of Cambridge and Prince Harry enjoyed a lavish night out on Thursday as they attended a special dinner in honour of their Royal Foundation.

The event was not announced by the palace but took place at Sunbeam Studios in West London, which is a quick 15-minute drive from the royal's Kensington Palace home.

Details of the dinner were kept strictly under wraps, although a guest shared a photo of her invitation on Instagram.

The invitation read, “The Royal Foundation of the Duke and Duchess of Cambridge and Prince Harry request the pleasure of your company at the Royal Foundation dinner.”

Accompanying the letter were instructions on how to get to the venue, asking guests to be there for 6.45pm, ahead of William, Kate and Harry's arrival.

The letter also added that photography and mobile telephones were strictly prohibited, and guests were asked to switch off their telephones upon arrival.

A professional photographer was present to capture the evening's events.

The dress code for the dinner was lounge suit and cocktail dress.

The dinner ended at approximately 10.15pm, and the Royal Foundation was the main focus of the event.

The foundation was launched by William and Harry in September 2009 and supports various charities close to the royal's hearts, notably in the sectors of mental health, young people, conservation and the armed forces.

Kate, who is pregnant with her third baby, was unable to attend the dinner due to her busy schedule, but earlier this week, she paid a visit to the Hornsea Road Children's Centre in London.

The Duchess had originally scheduled a visit to the North London Centre in early September but had to cancel last minute due to her severe morning sickness.

During her visit, Kate bonded with children and shared a fun fact about her two-year-old daughter, Princess Charlotte.