Beatrice's night out comes after news broke she was dating multi-millionaire property developer Edoardo Mapelli Mozzi.
Also in attendance at the Queen's lunch was the Duchess of Sussex and Duchess of Cambridge, who were alls smiles as they were photographed driving into the palace.
William and Harry drove their wives to the event with the second-in-line to the throne bringing his son Prince George and daughter Princess Charlotte, along with their nanny Maria Teresa Turrion Borrallo.
Meghan and Kate have been the subject of a series of media reports claiming there is a rift between them.
There have been allegations of a dispute over who reprimands staff, tensions during Princess Charlotte’s bridesmaid dress fitting, and claims that Harry and Meghan’s move from London to Berkshire reflects the widening gulf between the women.
But they both appeared relaxed as they arrived with their husbands, with Kate waving for the crowds outside the palace.