Royal Ascot's fashion police will be enforcing a strict dress code which has been updated and implemented for this week's event.
With 300,000 people expected to come through the turnstiles, the emphasis at the track will be on making sure that those who attend are dressed smartly.
As well as having a team of 'dress code assistants' on hand, there will also be a supply of waistcoats, ties and pashminas to smarten up anyone who does not meet the criteria.
Racegoers will be expected to meet differing standards depending on whether they are in the Royal Enclosure, the Grandstand or the Silver Ring.
Organisers sharpened up the dress code after criticism that sartorial standards had fallen in recent years.
The code was confirmed in January, and those with tickets have been issued reminders of what to expect.
Charles Barnett, Ascot chief executive, said: "Ascot is Europe's flagship race meeting and one of the world's greatest sporting and social events.
"We have tried to provide an appropriate dress code that is clear, workable and in line with the wishes of race-goers.
"Over the last few months, a huge amount of planning has gone in to making sure that the implementation of the new code goes as smoothly as possible. During the meeting itself, our team of special dress code assistants will help people with any queries that they may have."
Amongst the key rules, hats are a must for the Royal Enclosure, or failing that 'a headpiece which has a base of four inches (10cm)' is an acceptable alternative.
And for dresses and skirts, a modest length, defined as just above the knee or longer, is demanded.
For men, the dress code for the Royal Enclosure is black or grey morning dress, with matching top hat and shoes, while that is relaxed to a suit and tie in the Grandstand.
The event gets underway on June 19.