IT WAS during Inaugural Week, during the madness and glamor and glitter, that Jarvis the butler found out what the Californians really needed.

"They needed," said the Jefferson Hotel's night butler, "early breakfasts."

There they were, packed to the rafters of the sedate old Jefferson: the Coasties, the Kitchen Cabinet, the Californians who descended on Washington along with Ronald and Nancy Reagan. At one point during that late December, early January transition to a Republican Washington, the Jefferson sheltered five of Ronald Regan's cabinet nominees. The Californians breezed in and out of the 60-year-old hotel in their minks and their ball gowns, buzzing for pre-dawn breakfast that focused on fresh fruits.

"Californians," Ronald Jarvis discovered, "are health conscious."

To say the least. Jarvis holds the door for Defense Secretary Caspar Weinberger when he takes his 12-year-old collie, Mr. Buffington, out for his 10-minute jog each morning. Upstairs, at just about the same hour, presidential assistant Morgan Mason is probably pedaling away on the Exercycle he installed in his two-bedroom suite. As for Attorney General William French Smith, his major lament about life at the Jefferson is that it lacks the tennis court and billiard room he left behind in San Marino.

"But really," the attorney general was quick to demur, "it's about as much like home as it's possible to be in a hotel."

"Basically," said Rose Narva, the Jefferson's live-in general manager, "I think the people who stay here are looking for a home away from home, and that's what we try to provide.

"In places like the Watergate," Narva said, "It's like a city in and of itself, filled with lots of people. What we're trying to maintain is a place that afford privacy and intimacy without those crowds, a place that focuses on personalized services."

Indeed, the fact that so many Reagan appointees have chosen to make the Jefferson their Washington home -- temporary or otherwise -- would seem to support that. "At one point, late in December and on into January," Narva said, "we had among our guests the Weinbergers, the Smiths, Drew Lewis (Transportation), Ray Donavan (Labor) and William Casey of the CIA."

National security adviser Richard V. Allen camped out at the Jefferson during his first few weeks in Washington. Lee Annenberg, the new U.S. chief of protocol, spent her first six weeks there, in a spacious two-bedroom suite. "We just lost her," Narva said, a mildly disconsolate note in her voice. "She bought a penthouse in the Watergate." Even former Republican Sen. George Murphy checks in at the Jefferson whenever he comes to town, his friend William French Smith reports.

"We do meet from time to time, especially in the dining room," Smith said of this presidential traffic jam of upper-echelon Republicans. "But really, not as often as you'd think. Everybody has his own schedule."

Because there are so many top-ranking Reagan administration officials and GOP heavies in the 100-room hotel, some have taken to referring to the Jefferson, which is four blocks from the executive mansion, as the White House, north.

As Morgan Mason put it, "It's the Republican National Headquarters, no question about it."

Checking into the Jefferson, some of these administration hotshots bring human baggage along with their trunks and garment bags. The attorney general's driver, for instance, hovers in the hallway while his boss greets his guests in the Smith suite. And when certain clients of hotel owner Edward Bennett William's law firm, Williams and Connolly -- such as, recently, Mr. and Mrs. John W. Hinckley, parents of presidential shooting suspect John W. Hinkley Jr. -- are in residence, their security guards come along too.

At the Jefferson, however, these watchdog types manage to blend in with the wainscoting.

Even a few prominent Democrats, such as former attorney general Griffin Bell, have been known to slip into the Jefferson since the Republican takeover at the White House.

Still, stopping in for breakfasts and lunches at the Jefferson, hotel owner Williams manages to assume an air of bipartisan graciousness when he greets his VIP guests of both parties.

As Williams notes, "We don't ask for any political identification when you register."

"Mr. Williams," as ever diplomatic Rose Narva says of the burly lawyer, a longtime Democrat, "is a brilliant businessman."

One of the first things Williams did upon acquiring the Jefferson in 1976 was to lure Rose Narva over from the rival Sheraton Carlton. As general manager at the Carlton, Narva had overseen the $6.3-million renovation and transformation of that hotel from a comfortable, formerly elegant establishment into a glittering bastion of antiques and period refinement. She had upgraded the Carlton's dining room, spruced up the exterior and elevated, along with the price of a room at the Carlton, the service and ambiance of the hotel. When Narva and her husband, a Navy doctor, moved to the Jefferson, Williams gave her a mandate to work the same miracles at that hotel.

Narva accepted the assignment with characteristic modesty. "Mr. Williams," she said, "made a decision to do a little facelifting, yes." She immediately raided the Carlton for much of her new staff.

"Mrs. Narva," said Ronald Jarvis (better known at the Jefferson as Jarvis the Butler, or simply Jarvis), "is just a tremendous leader. She has this ability to draw on individuals." Jarvis is one of those individuals who followed Narva from the Carlton to the Jefferson. "With this charisma she has," Jarvis said of his boss, "well, she builds up interest in the hotel, and a tremendous loyalty.

"It's the details," Jarvis said. "Mrs. Narva emphasizes the details." Another staffer rolled her eyes. "She's a sticker, that one," she said.

Over breakfast in the peach-colored Gallery, Rose Narva smoother her black silk dress and wrapped elegant, well-manicured fingers around a bone china cup filled with fresh coffee. "What we're trying to do," she said, "is what most European hotels have been doing forever."

Williams agreed. "What I'm tring to do is simple. I have always thought that the Connaught in London is one of the three or four finest hotels in the world. I'm trying to replicate it."

And so, for rates ranging from $85 per day for a single to $150 and up for the larger suites (with discounts for prolonged stays), Narva's guests are met at the door, greeted by name and assigned to airy, spacious rooms furnished, in Jan Weinbergers's description, "like an English country house in the middle of the city." In the same English tradition, guests at the Jefferson get imported tea each afternoon. They get Turkish delight candies and tins of delicate English biscuits on their bedside tables at night. They get shiny black Spanish soup in their bathrooms. They get the shoe polishing services of Jarvis the butler. Best of all, at least in the opinion of Morgan Mason, they get Jarvis' all-night kitchen wizardry.

"He brings me fresh fruit at all hours," Mason said, "Blueberries, boysenberries . . ."

After several years of living in the Beverly Hills Hotel, it seemed perfectly reasonable to Mason that he would take up residence at a place like the Jefferson after he relocated to Washington. "It really is the perfect arrangement," he said. "It takes so much work to put together an apartment. And of course I would have to have some sort of staff to entertain the way I like."

It was once again Rose narva who acted as surrogate guardian angel in sparing the 25-year-old White House aide (known around the hotel as Eloise, after the fictional brat who inhabited New York's Plaza) the work of putting together an apartment. After installing Mason in a commodious two-bedroom place on the fourth floor, Narva began ripping out walls and combining several existing rooms to create even larger quarters on the sixth floor. The 40-foot-long living room in Mason's new suite will include a wood-burning fireplace and, so the young bachelor can entertain in private, there will -- "of course -- be a separate dining room."

Mason says he likes to cook -- but shrugs, why bother, when there is chef Paul Woods downstairs to whip up a little chicken curry (reportedly Mason's favorite), or maybe a dish of fresh-from-California Dungeness crab meat?

"Paul's approach to cooking," according to Narva, "is what the Californians are accustomed to eating."

"Californians are accustomed to eating a lot of fresh fruit," Woods has found. To accommodate this penchant, and to indulge his own culinary imagination, Woods has learned to carve virtually any fruit into the shape of a swan, and has taken to adding fresh fruit to some of the most unlikely sauces.

"The idea," said Woods, another Narva loyalist from their days at the Carlton, "is that a lot of our ideas abut eating start out on the West Coast and drift east. So you're finding a lot of lighter foods, and a lot more vegetarian and diet foods."

All night long, Jarvis said, he applies his own creative touches to the light suppers and fruit plates he ferries upstairs for the Californians. "Californians can be quite picky," he said, sounding more charitable than critical, more understanding than abashed. "They like to get their orders in just the right shape."

They are jovial, Jarvis said of his guest from the West: "they have such a good spirit."

Jarvis adds, "I can honestly say these Californians are full of money. They're just used to spending tremendous amounts of money." Again, the Jefferson's night butler sounded entirely empathetic with his condition. "Californians," he said, "are different individuals altogether."

"You know," said William French Smith, speculating as to why the hotel has become a haven for Republican power, "once somebody's there, others tend to follow."

Morgan Mason has another explanation. "It feels," he said, "like it's my house."