Queen Camilla was joined by some members of the King's extended family as she watched matches on Centre Court at Wimbledon on Wednesday.
Peter Phillips and his girlfriend, Lindsay Steven, were spotted among the guests in the prime seats.
The couple, who began dating two years ago, sat in the front row for the tenth day of the tennis tournament.
Dad-of-two Peter, 45, sported a navy suit with a purple tie, while Lindsay looked lovely in a blue floral-print Suzannah London dress.
Peter's younger sister, Zara Tindall, 42, and her husband, Mike, 44, were also among the spectators but the couple did not sit in the royal box.
The likely reason behind this is because equestrian Zara is a brand ambassador for Rolex, and so she sits in the seats designated for the watch company's invited guests, which are close to the Royal Box.
GALLERY: 12 of Princess Kate's funniest and most relatable reactions at Wimbledon
© Getty
© GettyBut who gets a say in who is invited to sit in the royal box?
Former press secretary to the late Queen Elizabeth II, Dickie Arbiter, previously revealed to HELLO!: "It's up to Wimbledon. The Wimbledon organisation makes so many tickets available to Buckingham Palace, some of them are in the royal box, some of them are in prime seats within centre court and those are distributed on a ballot basis."
© GettyHe added: "As far as filling up the royal box, well, it's really up to Wimbledon who they invite. They will be informed in advance if a royal wants to go or they'll send out an open invitation. Certainly, the Princess of Wales will go, she will go to the Ladies Final, she will go to the Men's Final on Saturday and Sunday respectively.
"She might well go on other days as well and her office will alert Wimbledon to the fact that she wants to go and when she will go, and Wimbledon will do the seating plan accordingly, leaving the sort of front row seats available. But Wimbledon likes to fill up the rest of the seats with celebrities and they don't have any difficulty doing that."
The Princess of Wales made her first appearance at the Championships last week, where she was joined by Swiss star and family friend, Roger Federer, in the royal box.
Kate also cheered on her husband, Prince William, at a charity polo match in Windsor last Thursday, and she was joined by William's cousin, Peter, on the sidelines.
Peter, who is the son of Princess Anne and her former husband, Captain Mark Phillips, separated from former wife, Autumn Kelly, in 2019.
© GettyThe pair, who share daughters, Savannah, 12, and Isla, 11, finalised their divorce in 2021.
Last month, HELLO! exclusively revealed that Peter has taken on a new role as head of partner acquisition for the sports and entertainment rights agency CSM Sport & Entertainment.
