The Army has removed a claim on its website that the Princess of Wales is reviewing Trooping the Colour in June.
Tickets were being sold on the official website for the June 8 military spectacle, advertising an appearance by Kate, on Tuesday evening.
The PA news agency understands the event details were published because of Kate’s role as Colonel of the Irish Guards, the regiment which is trooping its colour this year.
It also named the King as attending the main Trooping ceremony on June 15, also known as the Birthday Parade, because it marks the sovereign’s official anniversary, with bookings being taken for a ballot for tickets.
The announcement caused confusion because there had been no official confirmation from Kensington Palace or Buckingham Palace.
The princess has been seen being driven close to her home in Windsor after huge speculation on social media about the state of her health.
Only Kensington Palace, Kate’s official office, can announce her attendance at a royal event and confirmation is not expected until nearer the time.
An image circulating online shows the princess, wearing sunglasses, sitting in the front seat of a car being driven by her mother, Carole Middleton.
Since his diagnosis, the King has postponed all public-facing duties but is continuing with behind-the-scenes work on his red boxes of state papers and some in-person meetings.
Charles was pictured earlier on Tuesday during a pre-Budget audience with Chancellor Jeremy Hunt at Buckingham Palace, ahead of the financial statement on Wednesday.