Birthday Coordinate The dress code for my birthday event was black and red to match the Royal Princess Alice studio (and I really like the combination lol), so I wore 14 Royal Style Secrets Princess Catherine Has Mastered to Become an Icon New Exhibit Examines British Royal Family's Rules for Dressing Royal Family Rules & Dress Etiquette: Strict Traditions British Royals Follow Inside royal fashion protocol: The black outfit rule and other strict royal dress codes explained The Royal Dress Code Rules PS Fashion