THEY SAID it couldn't be done, that no newspaper

gossip column could ever succeed in Washington, a town dripping with gossip but woefully lacking in any sense of humor about its corporate self. It took a Brit, Diana McLellan, to prove them wrong.

By "they," of course, I mean that vast, amorphous mass of pols, presidents, pundits, party-givers and -goers, media people, lobbyists, spooks, sex maniacs, criminals and other status-seekers who are known to the rest of the nation as Washingtonians. By "they," in fact, I mean you.

The speed with which The Post snapped up McLellan's column "The Ear" on the demise of The Star last year, to the dismay of many of its habitual victims, was proof enough how much you love her. Unlike everything and everyone else in Washington, she never goes out of fashion.

It may be a chic party ploy to say The Ear's gone off, gone staid, gone soft; this means only that the speaker (a) is still an avid reader, and (b) is sore at having not been mentioned in the column lately. The odds are, morever, that he or she has already booked a post-party bitch-call to McLellan.

So here is a book to wallow in, even if you feel you can't be seen around town reading it (just slap any currently fashionable dust jacket over its garish exterior), or can't leave it lying prominently on the coffee table among the latest oeuvres of your other party guests. But be warned: if you leave it in the loo, you won't be seeing most of your guests all evening.

On hearing it was on the way, I feared at first that this might prove just another anthology of newspaper stories, like so many lazy products of every journalists's eternal quest for the immortality of hard covers. But no, McLellan has actually honed and polished her encyclopedic knowledge of recent Washington and its antics into the feistiest guidebook around. For every tale you've heard before, but are glad to be reminded of, there are two you can dine out on all year.

How wonderful to recall, for instance, that on leaving office Henry Kissinger didn't know his own way home; as the limo had whisked him back and forth each day, he'd been so absorbed in secret documents of cosmic geopolitical import that he'd never had occasion to notice where he lived. How life-enhancing to learn that President Reagan has had visiting cards printed, saying RONALD WILSON REAGAN, PRESIDENT, THE UNITED STATES OF AMERICA, just in case anyone's out when he calls.

Many old chestnuts are here: that Nancy Reagan's faith, for instance, is Christian Dior; or that marvelous request from the Carter White House, in the run-up to the 1980 election, for a really swank motorcade when the president arrived in Venice. (Think about it.) One of my personal favorites will always be the Washington Post picture caption which read simply: "Vice President Walter Mondale, right, inspects a turkey, left."

But McLellan is at her best when applying gossip, as in a wonderful chapter analyzing the eternal quest for status in Washington. Here is the small son of a Mr. Everyman columnist, opening his lunch box at kindergarten and crying "Oh, no! Not,e again!" and there is Admiral Stansfield Turner, issuing an order that no CIA staffer may barge past the director in the corridors, with the result that he is eternally seen marching at the head of his own private army.

Ear's three-page checklist of Washington status symbols ranges from "catching the president's cold" via "a desire in high places that you stay alive" (Secret Service escort, etc.) to "having a baby animal named after you at the National Zoo." She is equally good on the art of party- giving (and taking), summed up in the immortal words of Austin Kiplinger, he of the eponymous Report: "At any given party it's hard to know who's paying the bill, and for what motive you happen to be invited." Fellow scribes will no doubt warm to her judgment that journalists are "popular dinner guests, in spite of their table manners."

Ear is also blessed, as befits her name, with a good ear for a quote. One Georgetown hostess bemoaning Senator Larry Pressler's self-imposed exile from fashionable society: "A senator without gossip's like a pig without slop." Mayor Marion Barry, on leaving a restaurant called Chez Brown: "Chez, you put together a great meal."

There is a rather desperate chapter on sex -- Disgruntled Government Wife: "The only romance in town is the one with power"--which resorts to the old tale about the congressman who, in his haste to depart an illicit bed at dawn, inadvertently drank his date's contact lenses. There is a slightly disappointing section on the mavericks of the media, who are surely worth several volumes in themselves. But there is a marvelous examination of the rat-race for "access," that elusive privilege which even has lobbyists and other supplicants crashing the classier funerals to try a bit of button-holing.

"Is there life after Washington?" asks McLellan at the end of her nihilistic roller-coaster ride around town, creating such nostalgia in this recent departee that he is, though his friends won't believe it, stuck for a reply. Of those of you still carving your niches she says, in a characteristic bon mot: "The rest is history; we just don't know it yet." Courtesy of the Ear, I suspect we soon will.