The 21-year-old, who is the daughter of Prince Edward and the Duchess of Edinburgh, was pictured beaming as she took part in a horse driving competition in Norfolk.
Lady Louise, the eldest daughter of Prince Edward and Sophie, is believed to 'adore acting' and has been heavily involved with St Andrews Mermaids - which oversees student theatre productions.
Lady Louise Windsor looked to be in high spirits as she donned military gear and covered her face in camo paint while taking part in training with her university's officer's training corps.