The Duke and Duchess of Sussex will make their public return to Britain on Thursday for a royal reunion at Trooping the Colour, watching from a window as non-working members of the Royal family.
The Sussexes and their two children are invited to view the Queen's Birthday Parade, joining the monarch's grandchildren and great-grandchildren to view the spectacle from the Major General's Office overlooking Horse Guards Parade.
Senior and working members of the Royal family will travel in carriages in the traditional fashion, with the Prince of Wales, the Duke of Cambridge and the Princess Royal on horseback.
The Duchess of Cornwall and the Duchess of Cambridge will be among those making the journey from Buckingham Palace to Horse Guards Parade by carriage.
On Wednesday night, Kensington Palace would not confirm whether the three Cambridge children would be travelling in a carriage with their mother for the first time.
A spokesman for the Sussexes said the Duke and Duchess "look forward" to watching the event. The attendance of Archie and Lilibet Mountbatten-Windsor has not been confirmed and was said to be unlikely as of Wednesday, although a final decision will be made on the day.
The Queen will remain at Buckingham Palace for the duration of the event, taking a salute from the balcony at the end.
It will be the first time Prince Harry and Meghan will be reunited with their wider family since they left Britain for a new life in California in 2020.
Lilibet is making her first visit to her father's homeland, while big brother Archie is set to be introduced to his youngest cousins for the first time.
The Duke and Duchess are confirmed to be making their first public appearance for the Platinum Jubilee weekend at Trooping the Colour, albeit in a supporting role.
Along with the Queen's grandchildren, who do not perform official duties for Her Majesty, they will not be included in the carriage procession in which they travelled in 2018 and 2019.
That honour will fall to the Duchesses of Cornwall and Cambridge, whose husbands will be riding to Horse Guards Parade.
There, the Prince of Wales will take the salute and inspect the troops of the Household Division on behalf of the Queen, joined by the Duke of Cambridge and the Princess Royal.
The Earl and Countess of Wessex and their two children, the Duke and Duchess of Gloucester and Vice Admiral Sir Tim Laurence will be in other carriages.
At the end of the procession, the royal party will climb the stairs to the Major General's Office, also known as Wellington's Office, to watch the full spectacle from a vantage point overlooking the parade ground.
There, they will be joined by all the Queen's other grandchildren – Prince Harry, Peter Phillips, Zara Tindall, Princess Eugenie and Princess Beatrice – and their spouses, along with any of their children who would enjoy the occasion.
Also present will be the Duke of Kent, Princess Alexandra, Prince and Princess Michael of Kent, the Earl of Snowdon and his family, and Lady Sarah Chatto and her family. The Duke of York will not attend.
The attendance of the royal children will not be confirmed until the morning to allow for last-minute changes to their schedule through illness or nerves.
Seasoned royal-watchers will nevertheless hope for a full house, with the Queen's great-grandchildren usually attending Trooping with enthusiasm.
If they did attend, the event would give Archie and Lilibet their first glimpse of the British pomp and pageantry with which their father grew up.
Their cousins, including Mia, Lena and Lucas Tindall, Isla and Savannah Phillips, August Brooksbank and Sienna Mapelli-Mozzi, are all expected to join in the fun, watching the horses and riders of the Household Division.
The Major General's Office will afford them a measure of privacy, allowing them to step forward to the large open windows to watch the spectacle below or retreat inside out of the public eye.
The babies and toddlers of the family can appear for short stretches in their parents' arms without the pressure of being on their best behaviour as they would have to be on the more formal Buckingham Palace appearance alongside the Queen.
This year, the Colour of the 1st Battalion Irish Guards will be trooped.
At the end of the event, key working members of the Royal family will follow the Queen's instruction to return to the Buckingham Palace balcony for a grand finale, watching a flypast and waving to crowds. This year, it will include the three Cambridge children.
The Queen is expected to stay at Buckingham Palace for lunch with members of her family before being driven back to Windsor Castle for the night.
On Friday, adult members of the Royal family will be out in force again for a St Paul's Cathedral service of thanksgiving for the Queen's record-breaking reign.