Columnist George Will had planned it as just a small party, a chance for a few of his friends to have dinner with the president-elect. But by the time Ronald and Nancy Reagan arrived at Will's Chevy Chase home last night, the reporters and photgraphers were camped on the sidewalk.

The "Today" show had called. Come talk about your party, they said. The New York Times wanted him, too. And even Newsweek, for which he writes a column.

"Now that I relect back on the giddiness of Washington four years ago, I remember I was astonished," Will said. "So I probably should have known."

Speculating on who among the political columnists will be closest to and most knowledgeable about a new administration is always an active sport in Washington. So Will's party of 24, quiet as he wanted it to be, created a bit of a stir and set establishment Washington speculating about the guest list.

Which included:

From television, ABC's Roone Arledge; from the print media, Katharine Graham, chairman of the board of the Washington Post Co., and Meg Greefield, editorial page editor of The Post; from establishment Washington, Evangeline Bruce and former protocol chief Henry Catto; and from the military, Adm. Thomas Hayward, chief of naval operations.

Other guests were Vice President-elect George Bush and his wife, Barbara; James Q. Wilson, a leading policy intellectual; Irving Kristol, co-founder of The Public Interest; Yale Law School professor Robert Bork, a former U.S. solicitor general; Andrew Knight, editor of the Economist; Ed Meese, who'll be counselor to the new president; and the ubiquitous, peripatetic and indefatigable Robert Strauss, former campaign chairman for Jimmy Carter.

Will, the Pulitzer prize-winning columnist who has admired the president-elect since 1964, explained: "I am not an intimate of the Reagans. pAnd I am not an advisor. I'm just a fella. I sit out here in Chevy Chase and write columns." He also talked to Reagan occasionally during the fall campaign, once just prior to the debate.

The Reagans arrived at Will's home, a white frame variety that looks like it came from a John Cheever short story, about 7:30 p.m. The president-elect waved to a bunch of the neighborhood kids, shook a few hands, than scurried up the brick walkway to a front door hung with ribbons and Indian corn. His wife wore black silk and lots of fur.

Inside were a grandfather clock, two burning fireplaces and the same flush of victory that has followed Reagan throughout his week in Washington. "Delicious dinner," he said afterward."Wonderful, warm friends."

What he ate, in order: lobster pernod, stuffed roast veal, zucchini, carrots julienne, linguini vert, endive and watercress salad, raspberry mousse, macaroons, champagne and coffee.

The wine was Puligny Montrachet. The conversation, at three pink-ribbon-draped tables that held eight each, encluded cabinet speculation.

The dinner itself was arranged through Nancy Reynolds, a vice-president of Bendix Corp. here and a longtime friend of the Reagans'. After an initial dinner the Wills had for Reagan in April, when the candidate came but not his wife, Reynolds had relayed to Will Nancy's regrets -- and the suggestion that she'd like to come on another occasion.

So shortly after the election, Reynolds called Will again. "How about Thursday the 20th?" she said. And that was it.

Will, whose column is sydicated by the Washington Post Writers' Group, argued strongly for Reagan in the Nov. 4 election.

"He is a professional at the peak of his power, and he knows it," Will wrote in a Nov. 2 column. "He knows, and is at ease about, who he is, and what he is, and why . . . Although he leads a life impinged upon the endless distractions, he retains an openness to experience, a constant curiosity, an unforced enjoyment of things that characterizes people with a talent for happiness. So does Nancy Reagan."

Will is not the first columnist to know the informal side of a president, a side that is often vital to political information and analysis. The now-retired Joe Alsop is remembered as the one John Kennedy visited on his inaugural night; Lyndon Johnson attended Walter Lippmann's 75th birthday party. Later, because of the Vietnam War, Lippmann refused to get near Johnson, calling him the "most disagreeable individual ever to have occupied the White House."

Johnson retaliated by publicly criticizing him at a White House dinner. The guests were said to consider this quite gauche, but chances are, equally absorbing in a town long fascinated by the relationship between columnists and presidents.

"I'm dining with the Reagans," Will said, "not marrying them. It's obvious that I was not your basic undecided voter this fall. It's part of my profession to advocate certain ideas. The purpose of a columnist is to bring to bear a certain set of principles. It's a way of viewing the world, a philosophy."

Last night, at this third party in a row for the Reagans, Bob Strauss from the opposition camp might just have been the noisiest guest. He and Meese appeared to hit it off like two old pols.

Which prompted just the teensiest bit of speculation about what Strauss might do after Reagan takes office.

"You know what Ed Meese told me?" Strauss replied. "He told me he wouldn't be caught dead with me."