Royal Ascot is notoriously strict with its dress code.
Guests are encouraged to wear formal attire – and they can even be refused entry if they flout the rule book.
This year, bosses have made some changes to outfit regulations.
Here are RacingPost’s style tips that will prevent you from having a mare at the Berkshire races.
This year, racegoers are welcome to dress as they identify.
Ascot organiser’s hope this move will help transgender racegoers to “feel most comfortable”.
While ladies are permitted to dress in gentlemen’s clothes – and vice versa – their outfits must still be in keeping with regulations.
In the Royal Enclosure, skirt and dress hemlines must fall just above the knee or over.
Guests who don mini skirts could be turned away from the fancy area, so it’s best to go for a midi-hem to be on the safe side.
Ladies are also required to wear straps that are of one inch or wider.
Bardot tops, spaghetti straps and off-the-shoulder frocks are not permitted in the Royal Enclosure.
Those who don’t wear a hat or head-piece could also be committing a style sin.
Racegoers must opt for head-gear that has a base of four inches or more.
Fascinators are a big no-no, so it may be best to go for a feathered hat instead.
While jumpsuits used to be banned at Ascot, they are now permitted.
As of 2017, revellers have been allowed to rock the all-in-ones as they watch the races unfold.
While the Royal Enclosure is very strict with its dress code, its a bit more relaxed in other areas at the event.
In the Queen Anne Enclosure, women’s attire must still “be befitting a formal occasion”.
This includes wearing a hat, headpiece or fascinator, trouser suit and jumpsuit hemlines below the knee.
Those who wear shorts and have their midriffs exposed could be denied entry to the enclosure.
See-through or shoulder-baring garments could also attract a negative response from Ascot staff.
Meanwhile, men in the Village Enclosure are banned from wearing chinos.
Jeans and trainers are also prohibited, so get your glad rags on instead of dressing smart-casual.
Commenting on the most recent Ascot fashion changes, RacingPost.com’s resident fashion expert Katherine Fidler said: “Depending on your view, the Royal Ascot dress code is either a charming, quintessentially British tradition serving an annual reminder of our roots or an outdated, archaic nightmare, a five-day cavalcade of the country’s inequality in fashion show form.
“If you want to join the thousands of racegoers enjoying the action live, then the dress code is non-negotiable.
‘Even beginning to tread this sartorial tightrope is daunting enough!
“Most importantly though, remember – it’s not what you wear, it’s how you wear it.
“Don’t be intimidated by the four-figure price tags on show in Ascot’s official guide, high-street style holds up just as well.
“Of course, those more up with the zeitgeist than Oliver Brown or Victoria Beckham might wish to go vintage, saving a few pennies and the planet simultaneously.”