Some of the most famous faces on the guest list for Prince William's event were Kate Moss, Cara Delevingne, Cate Blanchett, Margot Robbie and Helena Bonham Carter.
Prince William chats to Emma Watson
Also lucky enough to have received an invite were Emma Watson, Benedict Cumberbatch, Mario Testino and Laura Carmichael.
William's wife Kate was, however, absent from the black tie dinner,
The Prince was hosting the event for the Royal Marsden cancer hospital, who are celebrating the news that Ralph Lauren is launching a new breast cancer centre.
Emma Watson, Cate Blanchett and Margot Robbie
The legendary fashion designer and his wife Ricky Anne made a rare foray away from their US home to attend the event.
William was introduced to Mr and Mrs Lauren at the event, and the Prince was quick to apologise for Kate's absence.
"I'm sorry my wife's not here, you probably would far rather you saw my wife," he said to the couple. Mr Lauren replied: "Not at all."
William mingled with his celebrity guests at a drinks reception before sitting down to a three course dinner, where they were serenaded by Emile Sande.
Ralph Lauren gave a rare on-camera interview ahead of the charity gala.
"I hate when people call me philanthropic because I see it as more coming from the heart," the 74-year-old says in a film to announce his partnership with the London-based cancer charity.
The video gives an insight into what has driven Ralph's longstanding commitment to fighting cancer; from his diagnosis with a benign brain tumor in the 1980s to the death of his friend Nina Hyde from breast cancer in 1990.
He has long been recognised for his early leadership in the battle against the disease, and was a driving force behind the annual Fashion Targets Breast Cancer campaign, which was launched in 1994.