The Queen will miss a ceremonial welcome for the Emir of Qatar, due to the lingering effects of her chest infection.
Camilla, 77, has been urged by doctors to rest and recover fully from the viral infection, which she contracted a month ago during the tour of Australia and Samoa and has left her with significantly diminished energy.
King Charles and the Prince and Princess of Wales will meet the Emir of Qatar and his wife in the UK on Tuesday, and will give him the traditional formal welcome outdoors on Horse Guards Parade for the official state visit.
William and Kate will meet Sheikh Tamim bin Hamad Al Thani and his wife, Sheikha Jawaher bint Hamad bin Suhaim Al Thani, in London. They will take them to the parade ground where the King and senior government figures will be waiting for the ceremonial welcome.
It will be Kate’s first state visit since her cancer diagnosis, as she gradually returns to a full schedule of duties after completing her chemotherapy in September.
The royals and their Qatari guests will travel to Buckingham Palace by carriage, before attending a lunch and visiting a Picture Gallery exhibition inside the residence.
Camilla’s programme has been adjusted, so she will now miss both the ceremonial welcome and the carriage ride. But she will join the Emir and his wife for lunch and hopes to be able to view the display in the picture gallery.
The Queen will attend the state banquet in the evening, and will join the group photo at the start before taking a short break before the meal while guests are met in a receiving line.
Princess Kate will not attend the banquet, but William will be there.
The Queen is also set to attend the Entente Littéraire Prize Ceremony with the wife of French president Emmanual Macron, Madame Brigitte Macron, as she returns to official duties. The ceremony will celebrate Franco-British literary talent and the special connections between the two countries.
On Tuesday afternoon, the Emir will visit the Palace of Westminster and address parliamentarians and invited guests in the Royal Robing Room. He will then join a reception with MPs and peers.
The Sheikh will hold bilateral talks with prime minister Keir Starmer, with some reports suggesting the government hopes to secure a free-trade deal with the Gulf Cooperation Council.
Sheikh Tamin, 44, who was educated at English public schools Sherborne and Harrow, will also visit William’s London home Kensington Palace, before visiting the King and Queen again at Sandhurst to formally bid farewell.