The Beefeaters strutted in their medieval costumes like an Alice in Wonderland pack of cards, cutting a path through the crowd for the queen. The chief Beefeater, bearing his rod of office crosswise, edged the crowd back where the lines bulged. Women in the front sucked in their stomachs, hoping not to lose ground. "I saw that!" the chief Beefeater said. "It won't do. Back, everyone! Or I'll send out the corgis!"

It was one of Queen Elizabeth II's four annual Buckingham Palace garden parties, on a hot afternoon last July.

Everything was all very good natured and polite, very paternalistic, with chuckles at the idea of the queen's little dogs on crowd control duty. Very British, very non-American. And with the wedding of Prince Andrew to Sarah Ferguson coming up here in just 10 days, it would seem instructive to compare for a moment the social life of this city with that of Washington.

If a summer reception on the White House lawn is Neil Simon, a Buckingham Palace garden party is Noel Coward. The basics are much alike: the well-tended lawn, the marquees for refreshments, the military bands, the well-dressed guests glowing with satisfaction about being there. But there any resemblance ends.

The queen, as a nonpolitical figure, is not to be reached for by eager egalitarian hands, nor slapped on the back by friendly citizens. Her palace is not the "people's house," as a president's is. And her guests are kept in order both by servants and by custom, lest they manifest any familiarity.

As the royal family moves slowly toward the royal tea tent, splitting up and taking different paths through the 8,000 guests, their progress is marked by a wave of curtsies and bows. But all is totally orderly, in contrast to the free-for-alls at the White House, where a president and first lady are surrounded by crowds eager to press the flesh.

Then, too, at Buckingham Palace there's the party within the party. Only those bidden to the royal tea tent actually get to mix and mingle with the royals. A giant semicircle chalked in white on the grass marks off the perimeter of the top tent. It is a bizarre sight to see the excluded majority watching from a distance, like the self-disciplined Brits they are, with not a toe over the white line, as cucumber sandwiches disappear down the royal throats.

The men's gray toppers, which they doff more often than they show off on their heads, are elegant. The women they escort cling to their arms, a garden of hats. Bishops stroll in magenta and purple cassocks, bougainvillea among the roses. And archdeacons straight out of "Barchester Towers" move along like black beetles in black top hats, tall clerical collars, stovepipe black trousers and square-tailed 19th-century black frock coats.

All is dignified. All is handsome. All is subdued. snoozes in a straight-backed deck chair, snoring gently. The band plays on.

Where in Washington every social set is drawn in some way into the centrifuge of politics, London is a collection of social circles that spin alone. Many "sets" flourish here. Magazines and newspapers chronicle and define them in detail as they emerge from the ranks of the well-heeled young.

For the older society set, the major events of the year are sporting: horse races, boat races, tennis matches. Then there's the Trooping of the Color for the military and the tourists. And the Buckingham Palace garden parties for the "provincials," "colonovincials," "colonials," clergy and local government types from around the country.

But for the young sets of London, life is one long party. The rich, hard-nosed Sloan Rangers (Princess Diana was a Sloan before she became a royal) have been joined by the New Georgians, conservation-minded romantics who live for old houses and country weekends, who wear powdered wigs at Georgian "Routs," sniff snuff and sip claret. Then there are the Eminent Victorians, whose passions are devoted to Gothic buildings; the Young Fogeys, High Tories of literary bent who wear chintzes and tweeds; the Hooray Henrys and Goodtime Charlies ('80s version of the old, less-than-bright Chinless Wonders). The latest group to be defined is the Drabbies -- "voluntary proles" whose raison d'e tre appears to lie in identifying with the oppressed.

Alexandria Artley, features editor of Harpers & Queen magazine, explains that the preoccupation with defining London's sets was an outgrowth of a 1970s obsession with sociology, and that these sets may be the last hurrah of people who have been able to make money and establish themselves socially.

Britain, she predicts, is about to become "very static for the first time in 50 years" due to recession, unemployment and limited opportunity. But that doesn't mean social life has to be boring. London has never been a "one-horse town" like Washington, Artley says. "Dr. Johnson once said about the complexity of London society, even in his day, that if you were tired of London you were tired of life."

Evangeline Bruce's London drawing room echoes her Georgetown residence as well as the decor of Winfield House in the mid-'60s when her late husband David Bruce was the U.S. ambassador here. There are melon-colored walls, luxurious curtains dramatizing tall windows, Aubusson rugs, moire-ribbon-hung paintings. Evangeline Bruce remains in the 19th-century Anglo-American tradition. She and her friends may jet across the Atlantic rather than sail on liners, but their connections in European society circles are deeply planted. Her guest one afternoon is Patricia, Countess Jellico, and over tea, the two women compare social life in London and Washington.

Washington, they agree, is the "exact opposite" of London in the way it absorbs new waves of people with each presidency. London, in contrast, is fixed, closed and set in its ways . . .

"Here you know if you go to Gavin and Rene's it will be the same crowd they invite to Scotland, always the same people," Lady Jellico says. "London parties, however, are mixed rather than all political, as Washington's are. There's always a writer or a painter, and even business tycoons are now being invited, because people are so fascinated by all these takeover bids . . . "

"In London I don't think anyone goes out of their way to meet a politician," Bruce says. "You never catch anyone by saying you're having the minister of such and such. In fact, I've heard people apologize for having them!"

Lady Jellico, who periodically lectures at Dumbarton Oaks and the Metropolitan Museum about Mogul India or famous gardens, observes that in London "the Cabinet doesn't go out to lunch any more. They used to, but they're all too busy today, so they all seem to have working lunches with fellow politicians at the House. However, it is like Washington in that you never know if they are going to come to dinner.

"But if they accept, they do come, unlike so many senators."

Parliamentary hours discourage London's hostesses from planning dinners around top political figures. Most evenings Monday through Thursday the House of Commons and the House of Lords sit late. If MPs do accept dinner invitations, they try to dine within "the sound of the bell" that calls a vote. If out of earshot, they keep an eye on their watches, stride off to Westminster when an important voting hour approaches and return later to the dinner party.

Power figures in London are more wary about being asked favors than those in Washington, Bruce and Jellico agree. Both also say that English men patronize women.

"One ingredient of British life is that men don't talk to women about their work. They want to talk rubbish most of the time," Jellico says indignantly. "It's difficult to have an interesting conversation with them, and they talk across you. They literally talk across you!"

Stag events are common in London.

As one American observes, "Women are light years behind here. For a country that has a queen and a woman prime minister, it's ludicrous."

The "fixtures" of the London season -- Ascot, Wimbledon, Henley, Glyndeborne -- cause everyone feels happy," Lady Jellico laughs. "They all dress up, so even if you are older, you don't look too bad."

Adds Bruce, who is famous for her elegance: "English dressing up is very special dressing up. English women are dressing better now, but there are still a lot of Christmas trees about."

Ascot, Wimbledon et al. give a coherent pattern and continuity to the social game and allow people to catch up with old friends. This is essential because established British society still spends most of its time in the country. London life is expensive, almost on a par with New York, and the streets echo with foreign accents. In their country retreats, the elite can turn the clock back, and more comfortably ignore the miseries of contemporary life. Old society, in fact, is like Middleburg coming into Washington several times a year for its social rituals.

In today's world, in which an Old Master painting may have to be sold to fund a "coming out" party for a 21-year-old son -- as in this summer's bash for "Champagne Charlie" Althorp, Princess Diana's brother -- old society spends its money judiciously. Dinners for six or eight old friends are the norm, big receptions and balls a rarity outside of charity affairs. Conversation in London, the women agree, is not political, as in Washington, nor "brilliant," as in Paris (where one must be on one's intellectual mettle), but "cozy."

If the United States had a parliamentary government, with a president playing only the ceremonial role, the White House would be Buckingham Palace, and a town house of some distinction -- like Blair House -- would be the residence and office of the prime minister. The roles would be split, as in Britain, where the queen is head of state and the prime minister head of government.

The constitutional difference makes comparisons between the two cities difficult. What's more, to truly imagine Washington in a London context, one has to graft onto Washington the major institutions of New York City -- the stock market, the arts world, the fashion industry -- thus diluting the capital's preoccupation with politics and government.

Margaret Jay, now a television journalist with the British news magazine "Panorama," was chatelaine of the British Embassy in the mid-'70s when her then-husband Peter Jay was ambassador. She believes it is impossible to compare No. 10 Downing Street -- where her father, James Callaghan, was prime minister from 1976 to 1979 -- with the White House.

"The head-of-state side of the White House is much more formal than Number 10, which is political," she says. "That constitutional difference must rub off on the way things are organized. Number 10 is basically an office, not a ceremonial home."

Jay, who has lived in Washington for several stretches in the past 20 years -- and who currently visits several times a year, regarding it as her second home -- insists that she is "out of the scene" in both cities, no longer attending the glossy balls and official dinners.

"I don't move in that world and never have, except for that period with Peter in Washington when there was an official role," she says. "The things I liked better in Washington are the same things I like in London -- life among my friends. The only difference is that London is so big, six months may pass before you see a friend, whereas in Washington, you're running into each other all the time."

Julie Nixon Eisenhower might say similar things about life after the White House. Yet a prime minister's after-hours life at No. 10 is as private as the first family's life at 1600 Pennsylvania Ave. is public.

Even when public money is involved, all social events are regarded as "private." Only a bare-bones paragraph appears in The Times Court and Social Circular after a party, with guest lists provided on "state" occasions. This is the tradition both at Buckingham Palace and No. 10.

Last Nov. 12, for instance, the queen gave a state banquet for the emir of Qatar. The printed guest list was not dissimilar from one at the White House: the visitor and his entourage, the Cabinet, ambassadors from about a dozen nations and their spouses, and names from the establishment such as the archbishop of Canterbury, several dukes and duchesses, the lord chief justice, a posse of generals and admirals, a football star and couple of opposition politicians. There were many more titles, but a similar establishment mixture. The same day Prime Minister Thatcher entertained the emir at lunch at No. 10, with a shorter, all-male, all-"working" guest list of about 50. No details were available from either the Palace or No. 10, nor were they expected by Fleet Street newspapers.

The queen gives two or three state dinners a year, many fewer than a U.S. president. Unlike at White House dinners, there is no entertainment. Otherwise the format is similar, with the queen toasting the visitor at the end of the formal dinner. State visitors stay as her guests at the palace.

She holds receptions periodically and has two or three private luncheons a year with about eight guests whom she hasn't met before. There may be a botanist who has discovered a rare orchid in Borneo, a scientist who has been in the news, or some other "interesting" people whom her staff think she'd enjoy meeting in an intimate setting. During Ascot week she'll have a series of "dine and sleep" parties at Windsor Castle, with about 14 guests on each of several nights, always including the prime minister and the Cabinet. This year there was a family fling at Windsor to mark the 21st birthdays of Prince Edward, Lady Helen Windsor (daughter of the duke of Kent), Lady Sarah Armstrong-Jones (daughter of Princess Margaret) and James Ogilvy (son of Princess Alexandra).

Prime Minister Thatcher, who lives in a flat above the offices at No. 10, gives two or three dinners and lunches every month, for 60 to 70 guests, the maximum the No. 10 dining room can seat.

She doesn't particularly enjoy entertaining, it is said, since as a workaholic she'd prefer to spend the time at her desk. But she keeps an eye on the details, supervising flowers and table settings herself and selecting the menus. For receptions of about 130 to 150 guests, a government agency called the Government Hospitality Fund accepts bids for the job, and menus with varying prices are given to the prime minister for her selection. Ham sandwiches, stuffed celery canapes and hot sausage may suffice for one group; salmon and crab may be required for another.

Occasionally a Conservative Party event -- such as the traditional end-of-session dinners for certain MPs -- is held at No. 10. Guests pay $25 each, since these are strictly "party-political" affairs. The prime minister's budget is modest by American standards. For No. 10 and Chequers, the prime minister's country residence, from June 1983 to March 1985, it was $50,000).

As at the White House, the chief executive's spouse plays a major social role at No. 10. According to Deborah Turner, the wife of Euro MP Amede Turner and daughter of Washingtonian Lillian Owen, Denis Thatcher's presence "makes everything relaxed. Without him the welcome wouldn't be the same. He cuts the ice, greets you, circulates. He's a lot like Prince Philip in that respect."

bat10 Turner is an American who has lived here for most of her adult life. She admits that the British are altogether more reserved and cautious about new friendships, but wouldn't swap London for Washington. "London, for all its troubles, is the center of the universe, more exciting on every scale," she says.

Much involved with her husband's "European" set and its European Community politics, and in the London music world, she draws an important distinction between the two cities' charity events. "Donations to charity are not tax-deductible here, so no one can afford to pay 250 dollars for a ball ticket, as they often do in Washington. If I had anything to do with national government, that's what I'd campaign for, because the arts suffer so much in that regard . . . "

Fred Emery draws another major distinction. The former Times of London bureau chief in Washington, now a top London TV interviewer, points out that in London "there's no such thing as social reporting. You can only do that in a small, homogenous community." He recalls how "miffed" No. 10 staffers were once when he wrote something after an event there. "Of course I'm going to write something, unless it says 'off the record' on the invitation," he,1

Betty Kenward of Harpers & Queen, who writes a monthly sweetness-and-light column called Jennifer's Diary, is the closest thing to a social reporter -- "the only one who's allowed, the only one who's proper," as Lady Jellico says. "She'll only say you're adorable and wearing a red coat," adds Evangeline Bruce.

Evening events in London are categorized as "private," and Fleet Street tugs its forelock and complies, not valuing the "soft" coverage that paints the watercolors of Washington life. Few people know what it's like to dine with the queen or the prime minister: whether the food is good or the conversation stimulating, whether "deals" are made on the fringes of a reception, whether visiting heads of state chide government leaders in the guise of making after-dinner toasts. Nighttime power operates behind doors firmly closed. The result is a vacuum in which gossip columns flourish, with predictably unreliable results.

Any given morning, the Court and Social Circular in The Times offers the bare facts of events the day before. Last Nov. 21, for instance, the princess of Wales attended a fund-raising ball. The "report" read: "The Prince of Wales, accompanied by the Princess of Wales, Patron of Birthright, attended the Birthday Ball in aid of Birthright at the Royal Albert Hall. Miss Anne Beckworth-Smith and Major Jack Stenhourse were in attendance."

But whatever happens in "official" life, the events worthy of a mention in The Times represent only a fragmentary part of social activity in a city like London. Old society holds its cozy suppers, careful with its budgets. Young society dances at the latest disco, careless of its expenses. Modish, punk-colored youth screams around the traditional social framework. The New Georgians gather around antique tables, sipping claret, yearning for an older, more gracious world. And the middle classes battle through the rush hour, home to suburbs as remote from the plush parties at Buckingham Palace and No. 10 as from the White House and Washington's social scene.

In the end, the dynamics of the social game -- the who-goes-to-what -- seems less important than the spirit of the two cities. Washington, with its vigorous political tempo, has a flexibility, absorbency and homogeneity that is sui generis. London, a bustling metropolis in a dispirited nation, is a complex society underlaid with history and class rigidity, overlaid with creativity and faddishness.

If Washington is a one-horse town, as its critics here (and there) maintain, then the horse is a lusty stallion. And London is an arena of circus ponies, cavorting in separate circles, blinkered eyes and Walkmen clamped about their ears, all dancing to different music.