Middleton wore an Alexander McQueen dress for those festivities, and Prince William swapped yesterday's military garb for his polo uniform.
George, dressed in beige shorts and a navy t-shirt, was pictured playing with a toy gun, toy knife and handcuffs.
Princess Charlotte, on the other hand, was too busy making her mom laugh during Sunday's polo event.
As the royal family (including the new Duchess of Sussex!) gathered to watched the planes fly past the palace, Phillips and George started goofing off a bit.
One comment said: "This was the only disappointing thing about today's polo match photos". My American side here, biased maybe b/c of everyday gunviolence in U.S., but my British side agrees.
But pictures from the day depicting George brandishing a toy gun cast a shadow on an otherwise happy day.
Prince George kept Kate entertained.
Parenting expert Sarah Ockwell-Smith told The Independent, "I understand why gun play worries parents, however research shows that any aggression demonstrated while engaging in "war play" is not carried over into real life.ie: kids who play with guns become no more violent than those who don't".
Princess Charlotte in particular, already known for her impeccable and charming foreign diplomacy skills despite her young age, proved to be the star of the show with some playful antics.
Many balked at the toys, given Britain's knife- and gun-related violence, which is "rising at an accelerating pace", according to the U.K. Guardian. Join the conversation over on our Facebook page and let us know your thoughts!