The King's cousin, Lady Sarah Chatto, was among the notable figures in the royal box on day nine of the Wimbledon tennis Championships.
The late Princess Margaret's daughter, 61, was joined by her husband, Daniel Chatto, 68, ahead of their 31st wedding anniversary next week.
Lady Sarah Chatto looked effortlessly chic wearing a crisp white ensemble, while Daniel sported a dark jacket, a pinstripe shirt and a blue printed tie.
The couple were seated in the front row of the royal box on Centre Court alongside actors Ian McKellen, Jodie Foster, Sienna Miller and Richard E. Grant.
The Chattos firstly watched the Ladies quarter-final match between Belarus' Aryna Sabalenka and Germany's Laura Siegemund.
An onlooker tells HELLO!: "Lady Sarah Chatto and her husband, Daniel, made a very discreet appearance in the royal box, but they were in good spirits and shared a laugh with Sir Ian McKellen during the break between the second and third set."
Close royal cousins
Lady Sarah Chatto is an artist who has exhibited her work at The Redfern Gallery since 1995.
While she does not carry out royal duties, she is often seen supporting her cousin, King Charles, at public events, including Royal Ascot, the Easter Sunday church service and Christmas.
Last month, Lady Sarah attended a star-studded reception at St James's Palace as the King and Queen celebrated 25 years of the Royal Drawing School.
Charles spoke warmly about his cousin in his speech, saying: He said: "I can't resist saying a few very small words because above all, I wanted to pay a very special tribute to darling Catherine [Goodman] who, can you believe it, it all goes back really to when my very special cousin, Sarah [Chatto], and Catherine were young 18-year-old students at Camberwell School of Art and used to come bouncing into my room. I remember that was where it all started."
Lady Sarah and Daniel married on 14 July 1994 at St Stephen's, Walbrook, in the City of London.
The couple share two sons – Samuel, born in 1996, who works as a sculptor, and Arthur, born in 1999, who is serving with the Royal Marines.