As the racecourse's style guide clearly states, "Ladies are kindly reminded that formal daywear is a requirement in the Royal Enclosure," at Royal Ascot.
So the news that Kristina Rihanoff of Strictly Come Dancing fame was escorted away from the enclosure on the second day of Ascot race is hardly surprising.
Her outfit? A mini dress made from betting slips.
The dress code requirements also state dresses should be "of modest length, defined as falling just above the knee or longer, and the straps on dresses and tops should be at least one inch wide."
The rules continue with a note that "strapless, off the shoulder, halter neck and spaghetti straps are not permitted, and midriffs must be covered."
Betting slips or not, Rihanoff's dress is definitely well above the knee in length and those straps could certainly be described as spaghetti-like.
As for the dress itself? It looked a little er, flimsy - which is probably Kristina made a quick change into a second outfit after being led away by an official from the racecourse.
The dancer was seen later on in the morning wearing a knee-length shift dress with a blazer and the same statement rose-coloured hat by London-based designer Ben De Lisi and it turns out? Kristina wasn't actually told to leave - her first outfit was merely part of a promotional stunt.
"It was always her intention to change her dress and she is still at Ascot enjoying the hospitality at the races," her spokesperson told the Daily Mail. Her Twitter page proves this too.
Still, Kristina isn't the only one to get heads turning at Royal Ascot this year - not when there's Zara Phillips, plus Princesses Beatrice and Eugenie to contend with.
Want to see more fabulous headwear? Here are all the fashion highlights from the first two days of the meeting: