Popsugar Fashion Kate Middleton The Royal Dress Code Rules There Are Very Specific Rules When It Comes to Dressing For the Royal Calendar June 25, 2017 by Marcia Moody View On One Page Photo 21 of 22 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 21 Epsom Derby — June Women: Formal daywear with a hat. Fascinators are OK, but they have to be "substantial." Men: Morning suit with top hat. Previous Next Start Slideshow The RoyalsKate MiddletonThe British Royals