There is only one place to be at Ascot: the Royal Enclosure. If you're not in the Royal Enclosure, forget it.

The Royal Enclosure is an area - the area - of the famous race course where the queen and the royal family go during the week of Royal Ascot, which was last week.

Though the first races were held at Ascot by Queen Anne in 1711, it was King George IV who erected in 1822 the first Royal Stand. George also instigated the now traditional Royal Procession, where they drive in carriages from Windsor Castle a few miles away, and the Royal Enclosure, as well, when he asked friends he had met on the course to join him on the lawn just below the Royal Stand.

The Royal Enclosure has grown in size to include a large courtyard behind the stands and the race course.

There are several enclosed restaurants, small white cabana affairs and there are terraces overlooking the courtyard and balconies off upstairs-restaurants as well, where guests may be served luncheons of potted shrimps, gulls eggs, strawberries and double cream and endless champagne, and where, naturally, they may take their afternoon tea. The entire area is spotless, with hanging flower baskets of geraniums, rhododendrons, acacia and other spring flowers and blue and white striped umbrellas and blue awnings. The air is redolent of fresh strawberries, melons and cucumbers mixed with the sweet smell of manure.

It is in the Royal Enclosure that everyone wears the clothes you've heard about and read about for years. The men must wear morning coats and top hats, the ladies day dresses and hats. Must. Otherwise you can't get in. Two Americans who tried this year to get in black tie and dinner jackets were thrown out.

One of them reportedly said, "We got rid of tails 30 years ago in America. This is our morning wear." (They were from Chicago.)

But they did have badges to get into the Royal Enclosure. Which brings us to the big question.

Who does get in and how?

According to the British aristocracy, the whole thing has been shot to hell.

One noble, strolling toward the paddock from the grassy slopes in front of the Queen's Box, spotted a man dressed completely in white: white top hat, white tails, white pants, vest, everything. He looked as though he had just stepped out of a Busby Berkely and he also looked suspiciously American.

The noble's lip began to curl slightly as only the upper class Brits' lips can curl in utter distaste "Reahllllly" he said to his companion. Lady Something-or-other, "It is dizzzzzzzgusting. They'll let anybody in these days."

Well. Not anybody. But almost. The trick is knowing it. Most people don't know that's it's easy to get into Royal Enclosure, so they don't even bother to try. And there is always the offchance that you may suffer a severe humiliation of being turned down for some unknown reason.

What you have to do if you're American is apply through your embassy. You have to know the dates when you can apply and once the lists close (this year on April 30), you're finished. They're very strict about that. Usually the embassy can get you in.

If you're British it's another story. You have to apply to the Ascot Office of the Palace of St. James's. In the old days after King George IV had begun inviting too many friends and it got out of control) you had to make formal application to the Lord Chamberlain and then afterward to Her Majesty's Representative at Ascot. And then, as now, you also had to be recommended by someone who was already accepted in the Royal Enclosure.

Vouchers, once obtained for the Royal Enclosure, are exchanged at the entrance for badges which cost 25 pounds, for all four days or 10 pounds for one day.

Nobody knows exactly how selections are made for the British, but there is supposedly a list of objectionables at St. James's Palace, and people are strictly screened. But more and more people are allowed in nowadays because when the new racetrack was built the capacity of the Royal Enclosure was increased to 4,000, which has pretty much eliminated any real social screening. After all, how could there possibly be 4,000 socially acceptable people?

It used to be that no divorced people were allowed in. And Princess Margaret, when she was seeing Peter Townsend (whom she later was forbidden to marry because he was divorced) apparently really worked the queen over on that one, for years to no avail. So, the story goes, it was only about 15 years ago that the queen was in her glass-encased Royal Box one day, surveying the crowds on the grass below, and inquired of one of her guests who all those people were. It was pointed out that, in fact, on that very lawn stood no less than 11 convicted criminals (high-class criminals, to be sure). The queen, reportedly horrified, remarked that if criminals could be accepted in the Royal Enclosure then certainly they should consider divorced people.They changed the rules shortly afterward.

At any rate, although there are a lot of elegant looking people who come to the Royal Ascot enclosure there are an unbelievable number of tacky ones too.

The breakdown goes like this: There are the royals and the truly aristocratic, titled Britons who go. The important thing to remember about these people is that they truly care about horses, raise them, own them, ride them, race them (yes, this is, afer all, a horse race). In that sense it's no different from Whitneys at the Kentucky Derby or the Mellons at the Washington, D.C. at Laurel. The upper-class horsey set dominates two races completely. After them are the rich people, not necessarily from titled families but with a lot of money.

Then there are the country squires, those who are interested in horses to some degree but even more interested in marrying off their eligible daughters to the nobles. You see an awful lot of young things in frothy flowered frocks of a marriageable age looking hopeful. And finally, there are those who everyone wonders how they got in. And apparently they are increasing in numbers every year. Many in that crowd are rumored to be Americans, and there could be some truth to that.

Politically, Ascot has a very conservative turnout.

There is another group, smaller in number, who go: They are the younger London smart set, ones who go to or own discotheques and trendy restaurants. Some of them have titles, some are aspiring to titles or to money. In Washington you might categorize them as the Pisces, Clyde's crowd.

It is also necessary to note who does not go to Ascot - the intellectuals, writers, authors, journalists, politicians, artists and actors. They would not be caught dead at Ascot. For instance, Peter Jay, the new British ambassador to the United States who will arrive next month, is 40 years old, brilliant, a columnist for The Times, a television personality, the son-in-law of the prime minister and an Oxford graduate. He has never been to Ascot. Offhandedly he will ask, "Oh, is it nice?"

Once a badge to the Royal Enclosure has been secured, the next thing one does is decide what to wear. For most men, except for the nobility, that means renting a morning coat and top hat. There is really only one place to go and that is Moss Bros. in London - a nightmare - several days before Ascot.

It used to be that gentlemen who wore morning coats (they can be black or gray) would be required to wear striped trousers, white wing collars, a gray and white-checked tie and a top hat. There even was a hatters shop set up outside the gates of Ascot for forgetful young men who had failed to bring their hats. But all that has gone by the wayside and the rules have become disarmingly lax. Moss Bros. will tell you that wing collars are no longer de rigueur. In fact Turnbull and Assers, the men's shirt shop on Ermyn Street in London, does a pretty good job of providing the men with colorful striped and plaids shirts and as for the ties, anything goes today.

Only the really old, really aristocratic men still stick to the conventions. Sir Alec Douglas-Hume wore a white shirt and a gray-and-whie checked tie and actually tipped his top hat every time he greeted a lady.

The ladies' dress is somewhat less rigid and leaves more room for imagination - and disaster.

The British female aristocracy has a penchant for the matching hat and dress, and mostly it doesn't work.

There are too many little dressmakers out in the countryside, stitching up the flowered prints and lining straw hats with matching materials, for everybody's good. There is certainly not the elegance or the chic one would find in a crowd of well dressed French or Italian women. However, the overall effect of a sea of flowered silk dresses, linen suits and big floppy hats is quite pretty. The hats, by and large, come from Herbert Johnson Hatters in London, where the proprietress claims to have sold more than 400 hats in the three days before Ascot.

Unfortunately, the hat thing for the ladies leaves the way open for every screwball in England to dream up any monstrosity she can for the event. None to be equaled, though, by the inevitable Gertrude Shilling, who has been coming to the Royal Enclosure at Ascot with her husband for 17 years. Her son is a milliner, and each year he dreams up something more atrocious than the last. Several years ago she appeared in a 3-foot-high jockey cap with streamers down the back. This year on the first day of Royal Ascot she arrived wearing a red, white and blue outfit with an 8-foot wingspan.

She was thrown out. Then Thursday, which is the special "Ladies Day" at Ascot and the running of the Gold Cup, Mrs. Shilling chose to wear an enormous hat of black ostrich feathers completely covering her face and a fox coat that was half black and half white. Explained Mrs. Shilling from underneath her hat, "I always have another hat with me just in case I get thrown out. This one's just an ordinary hat." Mrs. Shilling doesn't mind all the outraged comments she causes and grins through a gap in her teeth, shakes her platinum blonde curls and blinks her heavily shadowed eyes. "I love all the attention," she says. "It's lovely. Everybody looks at me.I always thought I would do well in Las Vegas."

Not everybody chooses to eat in lunches begins at noon so that everyone will be finished by the time the queen and other royals arrive at 2 and the first race begins at 2:30.

No indeed. Many of them drive their Rolls-Royce and an occasional Jaguar into the meadow nearby, which serves as a parking area, and have a picnic. Or at least THEY call it a picnic.

The important thing about the picnic is that you must bring your butler along to serve. In most cases, since there usually isn't room for everyone in the car, including the chauffeur and the butler, the chauffeur will substitute as the butler or vice versa. But they are sure to wear chauffeur's uniforms rather than the traditional tails for butlers, so as not to confuse. The butlers will lay the table - beautiful little baskets from Fortnum and Mason, fresh salmon, family silver and pretty linen napkins. With top hats and floppy flowered straw hats still perched on their heads, they sit and eat and gossip on the lawns until it's time to go and see the queen.

If the wind blows the ladies' hats they eat with one hand and hold the hats on their heads with the other, like Indian women keeping their saris over their heads out of respect for their husbands. One simply does not remove one's hat.Occasionally a cry will be overheard, "This bloody hat pin is not working at all," but they hang in there, grasping their hats as each blast of wind threatens without success to remove it.

The highlight of the day is the arrival of the queen in her carriage. the lords and ladies gather in the rear of the stands in the open courtyard about 15 minutes before her arrival and stand politely, chatting quietly to wait.When the queen's carriage and the other four behind her come into the courtyard, there is only the most discreet applause, muffled by white-gloved hands and a barely audible "h'ray" from the waiting group. The queen is accompanied in her coach by Prince Philip, Prince Charles and the Duke of Beaufort, followed by the Queen Mother, Princess Margaret, Angus Ogilvy, the Earl of Euston, and others.

The queen looked sensational on a most beautiful sunny Ascot day. She had chosen the perfect dress, a straw-colored linen dress and matching coat with simple, graceful lines and a jewel neck. She wore pearls and a simple diamond pin and a perfectly simple straw hat to match her coat. She was clearly the best dressed person there, seeming relaved and in a good mood. But then she always is when she's around horses, her passion.

Princess Margaret has on the same unfortunate pink thing she had worn the previous week to the Jubilee Thanksgiving Service in St. Paul's.

They stepped from their coaches and before they had disappeared into their box the crowd had begun to disperse. (It is good form to be respectful, but not good form to be overly enthusiastic. Shortly after the queen and the other royals had taken their places in the Royal Box the races began. Some of the spectators had actually purchased boxes, in which they ate their lunches before the race. There are 280 boxes which have a small dining room balcony and kitchenette and are serviced with maids and butlers. When the new race course was built in 1961 the boxes were rented, with prices ranging from $6,000 to $12,000.

The other seats in the Royal Enclosure are not reserved, nor are the wooden benches on the grassy incline in front of the Royal Box. Those seem to be the most popular. But actually, what everyone seems most happy to do is stand on the green and circulate like at a cocktail party during and between the races. That is, if they are not behind the track at one of the restaurants or cafes on the courtyard.

At some point in the afternoon the queen always leaves the Royal Box for a visit to the paddock.

This past Thursday was no exception. The queen, with two escorts, and followed by Princess Margaret, walked casually through the crowds toward the paddock. To get to the paddock, however, it is necessary to leave the Royal Enclosure and walk through what is called the Silver Ring, the next best thing to the Royal Enclosure. Though some people in the Silver Ring do try to tart themselves up and look as tatty as those in the R.E., it just isn't as glamorous. There are two giveaways. The grass in the R.E. is perfect, smooth, silky green. The grass in the Silver Ring is more mud than grass and the ladies found themselves near catastrophe, slipping in their high-heeled shoes in the muddy turf.

The second thing is that the minute the queen passes out of the R.E., and into the Silver Ring there is loud enthusiastic applause and audible shouting and yelling of H'ry. Nevertheless, the aristocrats, if they want to go to the paddock (and if the queen goes, they go) must grit their teeth and plough through the commoners in order to get there.

More important even than the paddock, however, is Whites. Whites is a very fancy men's club for the moneyed aristocrats in London. Every year during Royal Ascot Week Whites sets up a tent, a beautiful tent draped in pale blue and cream colored silk, and staffs it with the most fabulous buffet, wines, a very heavyset woman with a members list in her hand at the doorway to act as a bouncer to any unknowing person in the Silver Ring who might innocently wander in for a Guinness. Nobody from the R.E. would dream of going into Whites if they weren't members.

In fact, nobody in the R.F., even the climbers, the nouveau riches, the Johnny-come latelys and the gauche Americans would do anything they weren't supposed to do.

It's all a matter of form . It overtakes you. Controls you. Ascot is [WORD ILLEGIBLE]

Which is why it was so [WORD ILLEGIBLE] one of the ushers, a distinguished looking man in green velvet tails and a black top hat replied, when asked what his function was, "Why madam, my job is to make sure everyone in the Royal Enclosure behaves."