Their roles were to greet notable guest who were being presented to Princess Anne when she arrived. Each cadet was given a numbered paddle and were positioned around the circular walkway in the walled garden.
Anne greeted roughly 1000 people and also took time to speak to the cadets.
Princess Anne also went around other parts of the garden where she planted a tree, allowing other garden party guests to meet her.
The estate serves as home to the Secretary of State for Northern Ireland, and is the official residence for the Queen and other members of the Royal Family when they are here.