While US President Donald Trump and UK Prime Minister Sir Keir Starmer discussed global affairs on the final day of the historic state visit, Queen Camilla and Princess Catherine entertained the first lady, Melania Trump, in Windsor.
A library tour, miniature books, leaf printing and bug hotels were all on the agenda.
Before meeting up with the princess, Ms Trump joined the queen for a tour of Queen Mary's Dolls' House and the Royal Library at Windsor Castle.
The dolls' house, which is the largest in the world, was built between 1921 and 1924 for Queen Mary and designed by the British architect Sir Edwin Lutyens.
In the 1920s, authors such as Winnie-the-Pooh creator A.A. Milne, and Arthur Conan Doyle, famous for the Sherlock Holmes books, contributed special handwritten miniature volumes for the house.
"That's incredible," the first lady said while she admired the work on the miniature books, including The Gruffalo by Julia Donaldson.
Camilla and Ms Trump then met a group of school children who were writing and illustrating their own miniature books with colouring pencils as part of an art project.
Meeting the Squirrel Scouts
Ms Trump then joined Kate and a group of 20 children on the lawn of Frogmore House, a 17th-century country house near to the castle, which was favoured by Queen Victoria.
The children were part of the Squirrel Scouts, a youth organisation that was taking part in nature activities to earn their Go Wild badges.
Ms Trump helped them make images of leaves and build cardboard homes for insects.
"This is beautiful," she said as she sat down in a chair to examine the children's artwork.
The pair then awarded badges to the scouts for their efforts, with Ms Trump saying, "Congratulations!" and applauding.
The Princess of Wales also organised a special packed lunch for the children, which contained sandwiches made with honey from her Norfolk home.
Chief Scout Dwayne Fields told the BBC the event was a "great morning for all involved".
"Having the princess there alongside the first lady of the United States is going to be something very special for them [the children] in years to come," he said.
The interaction between the princess and Ms Trump was the first time the duo had come together for a royal engagement.
Business end of the trip
The first day of Mr Trump's state visit to the UK saw him surrounded by pomp and pageantry.
Amid high-level politicians, a media mogul, tech giants and athletes, the grandeur-loving president was treated to a glowing spectacle at a banquet at Windsor Castle.
But while Ms Trump spent more time on day two with the royals, the program for the president on Thursday was more serious as the prime minister hosted him at Chequers, his official country estate.
On his arrival at Chequers, Mr Trump was greeted by Sir Keir and his wife, Lady Victoria Starmer.
He was welcomed by a ceremonial honour guard complete with bagpipers and shown items from the archive of wartime leader Winston Churchill.
The two leaders enjoyed a lunch of Dover sole followed by key lime pie, and a display by the Red Devils army parachute team to commemorate the historic state visit.
At the end of the press conference, which covered a wide range of topics, the president and first lady posed for photographs with the prime minister and his wife before making their way back to London Stansted Aiport.
Small hiccup with helicopter forces emergency landing
But before they even made it to the airport, the president's helicopter was forced to make an emergency landing due to a minor hydraulic issue.
White House press secretary Karoline Leavitt said that the helicopter had landed "out of an abundance of caution".
"The president and first lady safely boarded the support helicopter … and were later able to board Air Force One for the return journey from the UK," she said.
The events capped off a two-day state visit that included displays of pageantry and a lavish banquet in which King Charles III and Mr Trump both remarked on the close relationship between the UK and the US.
ABC with wires
