Prince William and Kate Middleton
Tim Graham/Getty; Tim Ockenden/AP
12/15/2006 AT 04:40 PM EST
's girlfriend, Kate Middleton
, made it clearer than ever that she's a major part of his life when she joined the royal family to watch him graduate from his military academy
William, 24, was commissioned as an officer in the Household Cavalry as he graduated from Sandhurst in front of his grandmother, Queen Elizabeth, and his father, Prince Charles.
But it was Kate, also 24, widely tipped as the prince's future fiancée
, who grabbed all the attention as she walked to the historic parade ground with William's private secretary and two of his closest pals.
It was the first time she has been a guest of her boyfriend at an official royal engagement with the Queen present.
And Kate, stunning in scarlet, was clearly enjoying herself. Seated in the front row with her mother Carole (her father Michael was also there), she beamed as William made the traditional march past.
William was also grinning with pride. As the Queen made her own inspection of the young officers, the prince allowed himself a smile when she passed his line.
Middleton was expected at the graduation ball Friday night, where William and the other new officers will ceremoniously tear off the tape on their epaulettes to reveal the pips that signify their junior officer rank of second Lieutenant.
Next up, William will train to become a troop commander in an armored reconnaissance unit, following in the footsteps of his 22-year-old brother, Prince Harry.