The Princess of Wales has been spotted in public for the first time since Christmas Day, as speculation about her planned abdominal surgery and disappearance continues.

Kate, 42, was photographed by paparazzi sitting in the front passenger seat of a black Audi driven by her mother, Carole Middleton, on March 4 just after 9am.

Wearing dark sunglasses, Kate was near Windsor Castle when photo-hosting agency Backgrid took snaps of the mother and daughter, first published on US gossip website TMZ.

Kensington Palace has not yet commented, but sources told the Daily Mail the paparazzi pictures were not authorised as the palace has regularly emphasised Kate’s wish for privacy.

The public outing comes a week after the Prince of Wales unexpectedly pulled out of a memorial service for his late godfather, King Constantine II due to a “personal matter”, sparking concern about Kate’s ongoing recuperation at home.

On Wednesday (Australian time), there was speculation the princess would carry out her first major engagement since her operation when she will review troops ahead of the Trooping the Colour on June 8.

The British Army’s website contains the details and tickets are being sold for rehearsals for the annual military spectacle, which are a week before the Trooping the Colour ceremony.

The website also says the King will attend the main Trooping ceremony, with bookings being taken for a ballot for tickets.

Prince William and Kate, and their three children George, 10, Charlotte, eight, and Louis, five, were last photographed together in public attending a Christmas Day service at Sandringham.

On January 16, the palace announced Kate was undergoing planned abdominal surgery at the London Clinic. She was discharged after 13 days and has been convalescing at their home, Adelaide Cottage, in Windsor. She is not expected to return to public duties until after Easter (March 31).

In an initial statement from Kensington Palace about her surgery released one day after the operation, it read it was Kate’s “wish that her personal medical information remains private”.

The palace added that they would “only provide updates on Her Royal Highness’ progress when there is significant new information to share”.

The Princess of Wales (with sons George and Louis, and the King) at the royal family’s Christmas Day church service. Photo: Getty

Princess’ absence sparks online frenzy

Kate’s whereabouts have been the subject of bizarre social media conspiracy theories, from intended jokes and memes, to doctors and medical staff offering up their version of procedures on Reddit chat rooms and on X (formerly Twitter).

While the British press has trod carefully in updating Kate’s health, mainstream US media outlets have been more expansive.

Canadian-American gynaecologist Jennifer Gunter, a New York Times columnist and author on women’s health, and a specialist in chronic pain medicine, posted her theory overnight on X.

“The fact that everything was kept secret is testimony to how much senior royals collaborate with the press,” she said.

Many a Reddit commenter and casual social media user started chat rooms with a question: “What is going on with Kate Middleton?”, fuelling debate about what type of surgery forces a three-month absence from royal duties.

The Los Angeles Times tried to figure out the frenzy, highlighting the hashtag #whereiskatemiddleton as an ongoing talking point.

In response to William’s sudden cancellation last week, the NYT wrote about the “rumours swirling around” Kate and repeated one conspiracy theory published by Spanish journalist Concha Calleja a month ago.

Headlined The Curious Case of the ‘Disappearing’ Princess, Vogue weighed in, while BBC analysed the “royal dilemma” over Kate’s health.

The Prince of Wales with school children in Wrexham. Photo: AAP

On March 1, William was back at work celebrating St David’s Day in Wrexham and pouring beers at the local pub.

In a statement to The Sun, the palace said: “We were really clear from the start we weren’t going to provide a running commentary on the Princess of Wales’s health and only provide significant updates.

“Obviously, we’ve seen the madness of social media and that is not going to change our strategy.

“There has been much on social media but the Princess has a right to privacy and asks the public to respect that.”