Snowflakes swirled gently outside the Indian Embassy, and inside Washington's social and political cream lined up to meet visiting Prime Minister Indira Gandhi, here on her first trip during the Johnson administration as leader of India. March 1966.

Classic elegance filled the embassy. Expensive silks fluttered and trays of glistening hors d'oeuvres were passed through the grand rooms. Vice President Hubert Humphrey stood in the receiving line with Gandhi, greeting the several hundred guests. President Johnson was expected for cocktails. Only.

It was a black-tie affair. The president arrived at 6. In a brown suit.

Congressmen and diplomats, anxious to meet the prime minister, stood in a line that started at the front door and twisted and turned throughout the house. The president was also anxious to talk with Gandhi. He pulled her out of the receiving line to talk business. The guests eventually gave up and dispersed.

Dinner was scheduled for 7. At 7:30, the president was still talking with the prime minister. The guests were tired of the hors d'oeuvres, and the ambassador's wife was fretting. The clocked ticked away. Finally, the ambassador's wife approached.

"Mr. President," she inquired softly, "would you care to stay for dinner?"

"Weelll," drawled Johnson, "thank you. I'd just love to."

The wrong answer.

A corps of waiters scrambled to rearrange the dinner seating. As protocol demands, the president was placed on the hostess' right and a member of the prime minister's party was dropped from the head table. It was a hostess' worst nightmare come true.

It was The Party Horror.

"By the next morning everyone in town was screaming about it," recalls Mrs. Gladstone Williams, Washington's grande dame of protocol, who has been advising people on how to hold their fork for years. "I told reporters who called me that the president was from a big state where people just laid out an extra plate if someone unexpected came for dinner. He just forgot he wasn't in Texas."

On Washington's glittery social merry-go-round, where parties are as numerous--and sometimes as politically vital--as quorum calls and 30 seconds on the evening news, social disaster takes on a new dimension. The guest list is strategically compiled, seating is arranged strictly by protocol and the menu is planned weeks or months in advance.

Washington hostesses react to cracks in the party veneer like TV housewives react to ring-around-the-collar. Heaven forbid that the working press disrupt a formal party, or the food run out. It's simply gauche if a wife ends up seated next to her husband. Or, worse yet, if an ambassador is seated next to an official enemy.

"If you're the hostess, you're expected to be professional in Washington," says Jayne Ikard, wife of former congressman Frank Ikard. "Parties in Washington are very serious business. This is not a wildly gay party town."

Party woes become legendary--the dinner conversation at Averell and Pamela Harriman's house that showed up a week later on the front page of The Wall Street Journal. And Kay Shouse's indefatigable almanac hasn't gotten the weather forecast right in years for the annual Wolf Trap gala. Last year black-tie-clad guests ate under umbrellas and rings of water climbed up designer taffeta gowns.

Some tales of party gaffes in Washington even take on a life of their own. More than a few regulars on the circuit willingly relate how one hostess served undercooked lobster at a fancy dinner. And, they will tell you with authority, one of the crustaceans actually marched off the table. But the hostess in question says she never, ever served lobster.

"People think things out very carefully here and there are few impromptu parties," says Allison Le Land, the prominent Washington hostess who was a prote'ge' of "the hostess with the mostes'," Perle Mesta. "You could end up with an international incident over something simple like seating." You Are Where You Sit

"Protocol," sighs Joan Braden, hostess to ambassadors, senators and established Washington, "the biggest disruption in parties seems to revolve around breaches in protocol."

In a town that overflows with foreign dignitaries and fragile egos, battle lines are drawn when the pecking order is forfeited. According to the rules of the omnipresent Green Book, "The Social List of Washington, D.C.," the seating of diplomats should be determined by when an ambassador took his post in this country.

"I represent Charles de Gaulle in this country!" former French ambassador Herve Alphand once indignantly told Scotty Fitzgerald Smith when she asked him if she could breach protocol and seat Adlai Stevenson on her right. When the ambassador threatened to leave, Smith rearranged the seating. "It's just a mess when something like that happens," says Smith today. "You end up with wives sitting next to husbands and all that."

Friends, of course, may let an incident go the night of the party. But it is rarely forgotten. Like the time Joan Braden seated her good friend, then-secretary of state Henry Kissinger, nowhere near the head of the table. "He never said a word to me that night," recalls Braden, "but a few days later he said to Joe Alsop, in front of me, 'Do you know what Joanie did to me the other night?' " She says she has never done that again.

In Washington, a finely balanced ship of society, politics, money and power, any kind of seating fiasco could forever affect the pocketbook. At one large-scale fund-raising event this year, a Washington socialite was inadvertently seated next to her ex-husband. She called the next day to berate one of the party organizers.

"I do hope you realize," said the now-remarried socialite, "that this will certainly affect how my husband views this event next year." Senate Snags

To the outside world, having senators at a party appears to be a plum, but to those in the know, it could be the kiss of death.

"The bad manners of the Senate are enough to ruin any party," says author and hostess Susan Mary Alsop. "Twice this winter I attempted dinners at embassies--major powers where we just waited for hours for senators and they never called and never showed up."

"If you want to retain your sanity, never, never invite a senator to a party--no matter how sexy, charming or intelligent he is," says Sandra McElwaine, Washington insider and Cable Network News correspondent, "unless you want to be left with a hole in your table."

One spring, McElwaine invited four senators among her 20 guests for a Chinese garden seated dinner party. Two of them never showed, one was two hours late, and the fourth arrived on time.

"My wife decided not to come," that senator announced to the other guests, "because she was painting the basement." The Bungled Food

The National Gallery of Art is known for its sumptuous black-tie opening parties in the airy elegance of the grand foyer. The dinners, usually attended by Paul and Bunny Mellon and a guest list any Washington hostess would die for, are meticulously planned for months.

Last year, the gallery hosted a dinner to launch an exhibit called "The Far North," a collection of Indian art. Gallery officials thought serving reindeer would present a clever regional connection to the exhibit. They asked the caterer for a sample two months before the dinner. Reindeer it would be, they all agreed.

"During dinner," recalls Katherine Warwick, director of public relations for the gallery, "I happened to be sitting next to the only Eskimo who had come down from Alaska. 'You know,' he said to me, 'this is good but it certainly isn't reindeer.' I went into shock and asked the caterer if there was a mistake."

The entire shipment of reindeer hadn't arrived, explained the embarrassed caterer to Warwick. Some of the guests were fed liver instead.

Caterers, as well as all the party-service industries, are almost as frantic as hostesses in Washington. Competition is fierce. One bad rap and the party grapevine carries words that are bad for business. Consequently, when a caterer becomes involved in a Party Horror, he will be the first to admit it, and either adjust the bill or simply call the police to make everything all right.

Consider the time Ridgewell's was hired to serve England's visiting Princess Anne at a luncheon in Anne Arundel County. The fancy ice-cream desserts were still being prepared miles away as the diners started the main course. The ice cream and the purple Ridgewell's truck received a 40-minute police escort from Washington. It arrived on time.

During last year's frenzy of inaugural activity, 600 Avignone Freres bartenders almost didn't make it to the nine balls. "Someone called and canceled our order for chartered Metrobuses, and I had 600 bartenders just standing in the parking lot of Carter Barron Park with nowhere to go," says John Orcino, vice president of the firm. "So I called around in a panic and we ended up with Army buses and police escort." On and Off the Floor

No Washington party-giver is ever immune to Congress' erratic schedule. Not even the White House.

When an important vote is involved, the White House will provide chauffeured cars for senators who need to race to the Capitol during dinner. Such was the case during a state dinner in the Carter White House, June 1977.

"We invited about five senators," recalls former Carter social secretary Gretchen Poston, "and between the senators and the vice-president slipping out during every course, it was like playing musical chairs all night."

Those involved with the appropriations vote at issue missed most of the dinner. By the time the traditional toasts began at dinner's end, senators Dale Bumpers (D-Ark.) and Fritz Hollings (D-S.C.) were just tiptoeing in. Hunger struck. The two made their way to the kitchen and scavenged leftovers while the kitchen crew cleaned around them. Outside, the president raised his glass to Venezuelan president Carlos Andres Perez and two centrally located empty chairs.

Last year, when Luis Herrera Campins, the new Venezuelan president, visited the Reagan White House, the only surprise was Robert Goulet's nightclub act. "All I need is a girl . . . " he sang, gazing into Barbara Bush's eyes. In front of Nancy Reagan, he stopped: "That face, that face, it just isn't fair," he sang, walking and holding the microphone. "You must excuse me if I stare." He smiled and paused for air. "You're gorgeous." To Pat Haig he crooned: "Do you mind if I say you're cute in every way . . . "

And finally, at the end of his act, he poked former chief of protocol Leonore Annenberg in the arm and said "Wake up." The List

Several years ago, OAS Secretary Alejandro Orfila invited about 20 friends to dinner. Among them were a man and--unintentionally--three of his ex-wives. "I was quite embarrassed," says Orfila, although the evening went smoothly, "so I am very careful of my lists now."

Everyone is. There used to be a time when inviting the Egyptian and Israeli ambassadors to the same dinner would be considered an insult by both.

Uninvited extras are a sure path to potential Party Horrors. Last year, at the Organization of American States, twice the number of people showed up for a party catered by Ridgewell's. "We actually ended up rationing people on the buffet line that night," says Jeff Ellis, Ridgewell's president. "When it came time for dessert, it was only two petits fours per person."

For hostesses working off another person's list, there can be an element of surprise -- who's coming or not coming to dinner. Jayne Ikard had a small dinner for a New York business associate of her husband and his wife. It was during the Carter years, and one cabinet member said he would stop by at 8 for one drink. "He never left," says Ikard. "Every time I turned around, he'd be heading back to the bar."

The cabinet member was ultimately the last guest to leave. His long-waiting limo took him home at 12:30 a.m.

Meanwhile, at the same party, the guest of honor went into the newly decorated bathroom, with matching print wallpaper and shower curtain. As she was looking in the mirror, she leaned on what she thought was the wall and fell into the bathtub. Fly Me to the Moon

Alejandro Orfila, known for his lavish and frequent parties, says that his biggest Party Horror occurred at "Tango Night," a special Argentine party years back.

"I hired a firm to come in and polish the floors so that everyone could dance," says Orfila. "And boy did they do a good job. The floors gleamed like a mirror and were as slippery as ice. When the first couple got up to dance we never saw them again. They must have flown 10 feet off the floor and landed somewhere on the other end of the room. I was never so embarrassed." The Misplaced Minks

Two years ago Evangeline Bruce threw a party at her Georgetown house in the dead of winter. "It was one of those nights," recalls one guest, "that everyone seemed to be wearing the same color mink coat." And, as it turned out, one of those nights when some thought they would have to go home without their costly furs.

The coat checkers inadvertently placed the claim checks in the coat pocket instead of on the hanger in a visible spot. When everyone decided to leave at the same time, a traffic jam of mass confusion developed at the coat check.

"It was just awful and totally my fault," said Bruce's social secretary, Robin Young. "The people we hired to check the coats couldn't speak English and I fell short on my instructions. People were milling around forever waiting on their coats." Media Madness

The presence of the working media always poses an interesting a dilemma for Washington hostesses.

Two years ago attorney Steven Martindale, who climbed the social ladder through skillful party throwing, allowed an NBC crew to come into his house during a party he was having for actress Virginia Graham. NBC was doing a piece on social columnist Betty Beale, who was covering the party, and promised not to disrupt the gathering.

"Never again," says Martindale. "More people showed up than expected, and the cameras and stuff crowded the entire house, and no one could see under the glare of lights. They also taped down the wires and ended up tearing up half my carpet and the enamel on the dining room wall, which had been painted the day before. It was uncomfortable for everyone."

The seasoned Washington party guest, however, doesn't mind the glare of lights. In fact, many hope their best sides come through.

True Davis is sure of it. Last year, a movie production company was filming parts of "The Files of J. Edgar Hoover" at his sprawling northwest estate. Davis was asked to have a little black-tie dinner party on the outside terrace, which would serve as the perfect backdrop for one of the scenes.

"I have never seen so many hams in my life," says Davis. "Everyone was pushing each other out of the way to get in front of the cameras." Tell It to Me Slowly

Gerry Nettleton thought the best way to ease onto the Washington social circuit when she moved here from California eight years ago would be to throw a small, controlled dinner party with a select guest list. She had recently married Fairchild Industries executive Gil Nettleton and she drew up a small list of people he knew. She also sought the advice of an old friend, Vivian Dinitz, wife of then Israeli ambassador Simcha Dinitz.

"Always over-invite in Washington," Dinitz told her. "There are always so many other parties on any given night that only half the people show up."

Nettleton invited 70 ambassadors, congressmen and businessmen to her small, two-bedroom apartment for the party. Sixty accepted. A Party Horror by any definition.

"The day I found out," says Nettleton, today an experienced Washington hostess having learned the hard way, "I sat down and cried."