The Ascot race week is famous for being both a sporting event and its display of epic high fashion at its very best. One of highlights of the social calendar, the annual five-day horse-racing festival in Berkshire has been a staple of British tradition since 1711.

This year is no different, with Bollywood actress and former Miss World, Aishwarya Rai Bachchan among the big names in the paddock on the opening day. But Ascot is not just about celebrities... in fact, it isn't about celebrities at all. It's about fashion and it's about hats. More specifically, it is about women's hats.

Ask milliner David Shilling, who was stopped by Ascot-appointed fashion police in mid-week for not adhering to the strict dress code. The 56-year-old sported a large (and not very ornate) floral wreath on his head - an ostentatious piece of headgear that Ascot believes would have been better on a woman.

And that concern for what is and what is not appropriate - for both men and women - is being taken very seriously this season. According to Reuters, Nick Smith, a Royal Ascot spokesperson, organisers have decided to set clear guidelines.

For example, in the Grandstand area, women cannot wear strapless dresses or bare their midriffs. Also, no branded clothing is allowed and skirts must be of a "modest" length. Men must wear a shirt and a tie. And if you want to move further up the social ladder, women must wear hats and men must wear top hats, black shoes and morning dress.

"It needed to be reiterated that this is a formal event and we are proud of that although that does not mean that it has to be stuffy or old-fashioned," Smith told Reuters, adding, "There are not many events in society or real life where you have to dress up and people were glad we make the rules clear."

Should you be caught by Ascot's fashion police, you will be given a chance to atone - by buying a pashmina or tie for £5 or renting a top hat for £50. If you don't, you will be ejected.

Check out photographs of the penultimate day of Ladies' Day at the 2013 Ascot race weekend