Such a flap! Brouhaha! Everything askew!

"No!" shouts William F. Buckley Jr. from his vexed sprawl in the conference room of the National Review as the clock ticks toward the magazine's 25th anniversary banquet the next night.

The announced guest of honor for last Friday night, the standard bearer for The Cause, the vindicator of 25 years in the right-wing wilderness . . . won't be there.

Ronald Reagan.

There's been a terrible misunderstanding.

Buckley brandishes a letter sent in May by Reagan and denies -- "No!" -- that it contains any "ifs" about accepting the invitation to appear.

"The fact is last Sunday he said, when he first called me up and he found out that I was expecting him he called me up and said 'Bill, I've got this nowhere on my calendar.' And I said, 'Unless I'm crazy, you told me you were going to put it on your calendar.' And I was right. And he acknowledges that."

Buckley adds darkly: "In fact, he says he's going to redo his clerical procedures."

Well, watch out, Reagan office staff.

But pity Bill Buckley, who's in a throat-clearing, hand-waving fevor worthy of an undergraduate who has just learned that his date will not be arriving for The Big Weekend -- the celebration in question being the big anniversary banquet for 600 subscribers and supporters at the Plaza.

Could it be the fact that two years ago; when they found themselves on opposite sides in a debate over the Panama Canal, Buckley argued to Reagan: "The force of my illumination would blind you"?

"I've seen a lot of him since then," Buckley says. "That didn't affect our relationship."

All right: But the problem is exacerbated by the fact that Barry Goldwater just notified Buckley that he can't come either, and so Buckley has been beating the right-wing bushes for another apotheosis suitable to commemorate the unlikely fact that the National Review has lasted for a quarter of a century of maintaining a responsible and respected forum for conservative ideas, tilting against windmills and windmilling against tilters.

And now, in 1980, at the end of a decade in which the liberals seemed to have wrapped up power like a Christmas package . . . now, by God, Buckley can keep saying, over and over, as if he doesn't believe it himself: "We are the favorite magazine of the next president of the United States, who reads it from cover to cover and has written us to say so, a letter I'd be delighted to show you. . ."

And does.

Loping and leaning through the labyrinthine offices of the National Review, he finds the letter, gets someone to Xerox it, and returns to collapse anew in a swivel chair, eyes and teeth flashing like a startled vole's -- mannerisms that prevent Buckley from watching himself on his TV show, "Firing Line," because, as he has said, "Everything I do and say and the way I do and say it annoys me. . . ."

Anyhow: "The best you can hope for is to be the principal journal that instructs the president of the United States. I'll settle for that over against the fact that there are a lot of people who think we think the earth is flat. Let them continue to think it, is what I'm saying. I called him [Reagan] up and asked him if he would like me to change my description in 'Who's Who' from editor and writer to ventriloquist. And he laughed, but he laughed just a little bit too long, so I decided I wasn't a very good ventriloquist."

Twenty-five years.

Buckley, then 29, was five years out of Yale, having been editor of the Daily News and a member of Skull and Bones and everything else. At the same time, he was an enfant terrible, an entitlement that still wins him forgiveness from his ideological opposites. He was a millionaire's son, a Catholic and an activist conservative who raised nearly half a million dollars -- and a staff of former Communists and Socialists -- and announced the birth of the National Review, whose mission would be "to stand athwart history, yelling Stop."

The editors wrote in the fall of 1955 that "there is a Liberal point of view on national and world affairs . . . a hugh propaganda machine engaged in a major, sustained assault upon the sanity and upon the prudence and morality of the American people." They promised to keep a "watchful eye" on it. They received congratulations from people such as E. F. Hutton, Cecil B. DeMille, Adolph Menjou and Gene Tunney. By the following April, they'd caused enough alarm among liberals to provoke Dwight MacDonald to call them "lumpenbourgeoisie" and "McCarthy nationalists" in a Commentary piece entitled "Scrambled Eggheads on the Right."

They soon had a circulation that equaled or bettered liberal opinion magazines, along with enough controversy to provoke them to write in 1962 that they'd be grateful in their critics "if they would coordinate their attacks on us, so that they do not fall too thickly at any particular time."

Their style was and is marked by an ornate jocularity that MacDonald called "soggy facetiousness" but that has yielded wonderful puns -- such as the comment, when they learned that the American Academy of Dermatology and Syphilology was dropping the last two words of its title, that "skinicism is only sin deep."

The magazine, like the right wing, has been dogged by images of little old ladies in tennis shoes finding Communists under every bed. Buckley claims now: "We lost most of our kook readers the first year when we told them that Alaska was not in fact being prepared as a place in which everybody who voted against the censure of Joe McCarthy was going to be enclosed."

And if you can imagine a horse with Anglicized accent and eyebrows ascending toward each other, he laughs a horse laugh.

Other disappointments for some right-wingers have been: Buckley's decision to attack the John Birch Society and its conspiracy theories that had Dwight Eisenhower as an agent of the Communists; Buckley's advocacy of decriminalization of marijuana, and his backing of the Panama Canal treaty.

More recently, the magazine has been skirmishing with the neo-conservatives.

As contributor George Gilder wrote: "One of the continuing themes of neo-conservative thought is the existence of a horrifying spectre on the Right -- a terrifying chimera of conservative extremists -- nativist . . . bigoted, anti-Semitic, who would unleash holy war against the tolerant and urbane values of the welfare state. . ." Gilder says the very embodiment of this specter in neo-conservative minds is "the Buckley brotherhood."

Unfortunately for attackers, the magazine's offices, in an old apartment house on East 35th Street, are the sort of cozy, dingy, cluttered warren that everybody wants a little magazine to be. There are myriad yellowing cartoons taped to walls that bear even yellower hunks of tape that held a previous generation of cartoons and posters. MacNelly's versions of Jimmy Carter looking like melted wax are current favorites, along with the yachting pictures Buckley favors, and slogans such as a bumper sticker reading "Margaret Thatcher for President" (pasted up "before Reagan ran," says assistant managing editor Linda Bridges, with some alacrity). Because the four floors the Review occupies were once efficiency apartments, "there are more bathrooms than people," says associate publisher James P. McFadden, whose office is a comfortable jumble of old shoes, pipes, patent medicines, Oriental rugs and an autographed picture of Cardinal Cooke.

In fact, there are 39 people and somewhat fewer bathrooms. The staff has included columnist Garry Wills, whose liberalism has won him the title of "principal apostate"; novelist and essayist Joan Didion; and New York Times book reviewer John Leonard, who wandered in in 1959 after being told to take a year off from Harvard.

Leonard recalled recently: "I was offered $100 a week. I said I'd have to talk it over with my fiancee. Bill asked me where she was, and I said Radcliffe. He said: 'Tell her it's the New Republic, then.'"

Pranks have been numerous, including the "Swiss edition" in which a bogus magazine was mailed to a vacationing Buckley in Switzerland, incorporating everything he loathes -- references to himself unnecessary exclamation points, cliches and ungrammatical Latin (the use of the dative rather than the nominative case, as it happened).

One prank that misfired was the Pentagon Papers hoax, in which the Review printed as legitimate some faked documents describing a plan to detonate an atom bomb near Vietnam, winning the wrath of other publications who took the hoax seriously.

It was errant humor, Buckley says, that added to the Reagan confusion about the banquet. Buckley sent a reminder telegram to Reagan but signed it "Cinderella," he says, and now assumes it was routed either to a wastebasket or a bodyguard.

Priscilla Buckley, Bill's sister (and classmate of Nancy Reagan at Smith) came back from a United Press job in Paris to be managing editor, and she is generally credited with being the eye of the storm, both voice and ear of reason, and unmoved mover of the operation.

"When we first started," she says, "we had lots of people who demanded applause, attention and cajoling -- Willi Schlamm, Willmoore Kendall and Frank Meyer. Meyer said to me, 'You're the grease on the axle.'"

She could prank with the rest of them, however. "Very early on we ran a contest that was carried over five or six issues during the primaries. The idea was to guess who would get the nomination. There were 10 prizes. But it turned out the 11th person in contention was Arthur Schlesinger Jr. So we all chipped in $180 and bought him a donkey named Arthur and sent it to him. He sent it back to us."

As with Buckley's long acquaintance with John Kenneth Galbraith, however, the best of enemies can be best of friends. Besides, Buckley is persuaded that more people convert from left to right than the reverse. Converts made up the original staff, 25 years ago: John Burnham, Dos Passos, Max Eastman, Whittaker Chambers.

And now?

Buckley scans the masthead. Very quietly, he says: "Gee, they're just about gone, aren't they?"

An era is ending.

Some of the staff worry about how the magazine will cope with the next four years, if not the next 25. After all, their specialty is pointing out that the emperor has no clothes. Now, they've got their own emperor.

As far as sense of humor goes, the post-election issue informed its readership that it would be "the last issue in which we shall indulge in levity. Connoisseurs of humor will have to get their yuks elsewhere. We have a nation to run."

Friday night, 600 people -- most of whom number themselves among the "we" -- gather under the gilded ceilings of the Plaza ballroom. His swivet behind him, Buckley has dining companions who include: Henry Kissinger, Clare Boothe Luce, probable CIA chief William Casey, Senator-elect Alfonse D'Amato, Walter Cronkite, lawyer (and old Joe McCarthy aide) Roy Cohn, futurist Herman Kahn and columnist George Will, who was once the Review's book-review editor and who fills in for the missing Reagan and Goldwater.

Buckley, in his speech, repeats Reagan's statement that he has been reading the Review for 25 years, the knowledge of which, Buckley says, gives him "girlish pleasure." He confesses, however, a certain regret at practical politics: "Familiarity with the processes by which public policy and sausages are made would kill the appetite for either. Still, there is pleasure in even a little progress, even among those of us taught, at our mother's knee, not to seek to immanentize the eschaton." (The final salvo there was once a catch-phrase and private joke among the Young Americans for Freedom.)

The day before, slouched in his chair in the conference room, Buckley is reminded that one columnist has predicted that the right wing would be raging about Reagan betrayals by May.

Buckley mulls. He drawls. He flashes the eyes. "If he woke up one day and said, like Sadat, 'I renounce my past,' I would say he's an apostate. Ronald the Apostate. But I don't anticipate that happening. If that should happen. I would argue that indeed people were correct in predicting senescence."

He laughs a very big laugh indeed.