The Duke of Sussex will join the Queen as she hosts a lunch for Donald Trump at Buckingham Palace on the US President's first full state visit next month.
His American wife, the Duchess of Sussex, is on maternity leave and will therefore avoid a potentially awkward encounter with Mr Trump, whom she has previously described as "misogynistic" and "divisive".
In 2016, the Duchess, who gave birth to Archie Harrison Mountbatten-Windsor on May 6, said she was backing Hillary Clinton in the presidential race because she did not want "that kind of world that (Trump) was painting."
Mr Trump might also be advised not to mention Diana, Princess of Wales, whom he once suggested he could have slept with.
The private lunch will take place shortly after Mr Trump's arrival on June 3, following an official welcome by the Queen, the Prince of Wales and the Duchess of Cornwall.
The younger royals were expected to play a part in the three-day visit after it emerged that the President planned to bring four of his five children with him.
Palace sources confirmed that the Duke and Duchess of Cambridge will attend a state banquet hosted by the Queen during his first evening in London.
The white-tie dinner will be attended by some 150 royals, politicians, advisers and other guests who will mingle in Buckingham Palace's ballroom.
The full itinerary for the visit, released by Buckingham Palace yesterday, reveals that the Prince of Wales will share official duties with the Queen as he increasingly assumes greater responsibility to support his 93-year-old mother, as he prepares to one day be king.
He will jointly inspect a Guard of Honour with the US President and will later host Mr Trump and his wife, Melania, for tea at Clarence House.
The following day, Prince Charles and the Duchess of Cornwall will attend a dinner hosted by the US Ambassador on behalf of the Queen.
They will then joined the Queen and the Trumps on June 5 for a D-Day 75th anniversary celebration in Southsea, Portsmouth.
The Prince's heavy involvement in the state visit is in marked contrast to Mr Trump's first official visit to the UK last July, when the pair did not even meet.
It will be seen as a clear sign of his readiness to assume the throne and a demonstration that he is prepared to put personal opinions on matters such as climate change to one side as he prioritises the monarchy.
The visit is expected to attract up to a million protesters, which will require one of the biggest policing operations undertaken in the capital.
But the absence of any public, outdoor events, will likely avoid potentially confrontational scenes.
Mr Trump's arrival will be marked by a Ceremonial Welcome in the Buckingham Palace gardens and Royal Gun Salutes fired in Green Park and at the Tower of London.
After the private lunch attended by Prince Harry, the Queen will invite the Trumps to view a special exhibition in the picture gallery at Buckingham Palace showcasing items of historical significance to the United States from the royal collection.
The Trumps will then be joined by the Duke of York for a visit to Westminster Abbey, where the US President will lay a wreath at the Grave of the Unknown Warrior.
They will then have tea at Clarence House ahead of the state banquet at Buckingham Palace.
On June 4, Mr Trump will hold meetings with Theresa May at Downing Street in the dying days of her premiership.
The pair will co-host a business breakfast meeting at St James's Palace, attended by The Duke of York and senior British and American business leaders.
They will later have lunch together before holding a joint press conference.
That evening, the President and Mrs Trump will host a return dinner at Winfield House, the US ambassador's residence, attended by the Prince of Wales and the Duchess of Cornwall.
The following day, the official party will decamp to Portsmouth for the National Commemorative Event for the 75th anniversary of the D-Day landings before the Queen formally bids farewell to her guests.
The American party will include Ivanka Trump and her husband Jared Kushner, Tiffany Trump, Donald Trump Jr and Eric Trump and his wife Lara, despite some having no formal role with the US administration. The President's youngest son Barron, 13, is not expected to join them.