Special Friend Visits Reagan on Birthday : Celebration: Former British Prime Minister Margaret Thatcher attends a party for the ex-President, who turned 80.

There was a moment--standing knuckle to knuckle and smiling into the round eyes of the cameras--when Margaret Thatcher and Ronald Reagan looked like the partners of their glory days. From the Williamsburg summit, perhaps, or Versailles, when he, the captain of the Free World’s ship, and she, his first officer, had prodded and outraged and cajoled and bent the world to their will.

But here and now is a hilltop in Simi Valley. Here and now they are both ex, former, both cold warriors consigned to watching the world go to war without them.

Reagan awaited her outside his unfinished presidential library, framed by concrete pillars the size and shape of Sidewinder missiles. The Iron Lady--the Soviets coined the term and Margaret Thatcher embraced it--slid out of a black Cadillac and walked up, beaming. It was a mellow walk, not her old ministerial stride, when the high heels seemed to dig holes deep enough to plant seed corn in.

Reagan kissed her on the left cheek. “Oh, thank God,” breathed the British photographers, who had feared a mere handshake. “One more, one more,” they begged greedily.

Thatcher, who resigned in November after about 11 years as Britain’s first woman prime minister, remains what Reagan calls his political “soul mate”--his “special friend,” as he said of her Wednesday night at his 80th birthday party. In his Century City office, her autographed picture sits in view, off to his right.

It was his birthday that Thatcher came to celebrate. The last time she was in California was 1969, as a member of Parliament whose party was out of power. She planned to come three times since. Once, the World Affairs Council even had the invitations printed when she canceled.

Now she is just an MP again, but with a difference. In a town that knows how to weigh star quality ruthlessly, she does not fall short. Certainly she was more adoringly received here than she might be in some British town stung by unemployment or the poll tax. She was applauded by 2,000 workers at the Jet Propulsion Laboratory, by the lunch crowd in the celebrity room of Universal’s studio restaurant, by refinery workers in Carson.

Hers was not a laid-back itinerary; Margaret Thatcher does not frivol. The closest she got to glitz was a Universal Studios lunch with MCA chief Lew Wasserman, and a chat with actress Angela Lansbury on a sound stage. For the rest, she was absorbed by a new fuel made in a Carson refinery and engrossed by telemetry signaled back from Magellan as it orbits Venus.

Last December, she was only days out of office when two friends showed up in London and invited her here: Reagan and Arco Chairman Lodwrick Cook, who heads the library fund-raising effort.

Arco underwrote her visit. An Arco helicopter flew her around. She stayed two nights in Santa Barbara at Arco’s conference center/residence. She lunched in the Arco Towers, roamed the huge Arco refinery, which she pronounced “quite the cleanest refinery I have ever seen.” She toured Santa Cruz Island, a vast Nature Conservancy preserve purchased in part with a $1-million Arco donation in 1978.

Her husband, Sir Denis, who has an interest in retailing, spent about 90 minutes at a Mid-Wilshire area Arco am/pm mini market, tasted the vanilla frozen yogurt with Heath bar crunch topping (no relation to the former prime minister).

The Thatchers flew here on an Arco jet, stopping for refueling in North Dakota, where locals gave them chocolate-covered potato chips. Before she leaves today, she is scheduled to lunch at Nancy Reagan’s favorite restaurant, where the tab for a dozen will reportedly be picked up by Arco.

The Arco name loomed so large in the itinerary that a British reporter remarked: “Now she knows what we’ve all felt like, being held hostage by the oil companies.”

MONDAY

A trio of copters took the Thatchers to Simi Valley.

As Reagan waited at the library, some among the press corps began a ragged chorus of “Happy Birthday.” The British were astonished. One suggested: “Maybe we of the British press should lead a chorus for Mrs. Thatcher of, ‘Ooh, You’re Out, Ooh, You’re Out.”

Thatcher has never exuded Ronald Reagan’s warm fuzzies, never inspired that kind of affection. Her persona has been more formidable, half the hectoring nanny, half Boadicea, Britain’s 1st-Century warrior queen.

Ex-prime ministers, she has complained, get something of a bum’s rush “into the street.” At the lavish Reagan Library, at the gala Reagan birthday dinner, she could not help but notice the difference. Reagan was basking in the stirring visual events banked around him like bouquets. In Britain, it’s the queen who takes the bows.

And Reagan, whose allotted eight years ended with an orderly passing of power, likes his ease. Thatcher, who quit when her own party suddenly yanked its support, clearly does not.

Out behind the library, she admitted, “Oh, yes, of course” she missed being in charge. “Who wouldn’t? After 10 1/2 to 11 years, who wouldn’t? But we had 10 1/2 to 11 years and that is actually longer than a President of the United States is allowed.” And as for the Persian Gulf War, she reminded reporters eagerly, “I was in on it from the beginning, as you know.”

The Queen made Thatcher one of 26 members of the Order of Merit. Her husband was made a baronet, but she wants to be called “Mrs. Thatcher,” the name she will carry into the history books.

“I have given no further thought, no further consideration,” to a peerage, she said Monday in a voice as firm as her chin. To accept a noble title would mean leaving the green benches of Commons for the red seats of the House of Lords, and its sort of fifth-wheel role in government. At 65, she is not ready for that.

But they cheered her like the Queen herself at the JPL in Pasadena, and Thatcher, after her initial astonishment at a crowd calling “Margaret!” shook hands amiably.

The woman who once made it clear that she could run a government efficiently because she could run a house efficiently drank English breakfast tea and told the cluster of scientists in her best nanny-voice, “We’ve had enough astronomy. We’re talking about tea, a really important subject.”

Scientists were impressed with the expertise of the woman who studied chemistry at Oxford and reads Stephen Hawking’s books for fun.

Thatcher is not the sort of woman to inspire bouquets, but Vardkes Boyadzhyan, 29, brought a red rose from his wife’s flower shop and Thatcher stopped to take it. “I’ve heard about her all my youth--she was the Iron Lady,” Boyadzhyan said. It didn’t bother his wife that it was for another woman. “It’s not another woman,” he said. “It’s Margaret Thatcher.”

TUESDAY

Tuesdays were always big days for Thatcher. In the afternoon there was Question Time, 15 minutes in Parliament when the opposition got to take its best shot at her in what the British like to call the cut and thrust of debate; it was for good reason that the opposing front benches in the House of Commons were set two swords’ lengths apart.

“The adrenaline flows when they really come out fighting at me and I fight back and I stand there and I know: ‘Now come on, Maggie, you are wholly on your own. No one can help you.’ And I love it,” she said once. It helped to make her a star.

On Wednesday night, Merv Griffin admitted he “fell in love with her on C-SPAN,” watching her take on “those 600 bullies in the House of Commons.”

This Tuesday, about the same time that she would once have been ushered into Buckingham Palace for her weekly meeting with the Queen, she was wearing a periwinkle-blue suit and racketing in a dusty open Jeep across Santa Cruz Island, looking over the Nature Conservancy’s project to preserve the 10 native plant species found only on the 96-square-mile island.

She asked about the drought, and the botany. “She said one of the things she likes to do on these trips is get out and see some science programs in operation,” said program director Jim Sulentich, admiring her resoluteness to do what she wants. “If her interest were shopping I’m sure she would have been shopping.”

WEDNESDAY

There was not the gratification of seeing Thatcher in a hard hat, but for 90 minutes she popped in and out of labs and turbine generators and lectures about reformulated gasolines, Arco’s newest entry in the clean fuels category.

In a chilly room where the huge breakers for 300,000 volts of electricity purred, she charmed 45 blue-jumpsuited workers, congratulating them on their tidiness and efficiency, both important traits in the Thatcher book, and confided that “I’ve also learned . . . that we’ve got to buy a new car,” to replace their well-tended 8-year-old Ford.

She was classic Thatcher, applauding and nudging them toward their clean-air efforts, “if you really put in your very best and a little more to attain it.”

The ritual of food divided the rest of the day: lunch at the Reagans’ home on St. Cloud Drive, then dinner with the Reagans and 900 of their closest personal friends at the birthday event.

Thatcher, in gold brocade and black velvet, walked into the dinner with the Reagans. Nancy Reagan walked between the two former leaders, holding hands with them.

Thatcher phrased her praise for his career “in terms familiar to many in this audience,” comparing it to films from “Andy Hardy” to “A Star Is Born,” then “Mr. Smith Goes to Washington.”

Reagan’s late-blooming presidency, she remarked dryly, “is quite an incentive to those of us about to start on a new career later in life.”

She took a few rhetorical swats at communism and at critics of Reagan’s military buildup--”How ill-judged that criticism looks today. I am proud to have been beside you,” she said, “when you held high the torch of freedom.”