It looks like the young royals enjoyed the day overall. Photos from the event showed George and Charlotte playing with Savannah on the lawn. Their baby brother, Prince Louis, was not in attendance.
This isn't the only mischief Savannah got into this weekend. During Saturday's Trooping of the Colour event, the little lady covered George's mouth while he attempted to sing "God Save the Queen."
Savannah is the 7-year-old daughter of Peter Phillips, son of Princess Anne, and Autumn Phillips. She is also fifteenth in line for the throne.
However, George is third in line to the throne. So, Savannah may want to be nicer to her little cousin.