Queen Elizabeth II emerged from her burgundy Bentley, a whale of a machine with the Royal Standard flying on a little flagpole on the roof, and stepped onto the sidewalk on a cool London evening. The monarch was elegant in her ivory dress and pearls, all sequins and smiles and regal radiance amid the electrical storm of photographers' flashbulbs.

But it was the woman waiting for her Thursday night who stole the show.

A little wobbly now, moving with the caution of great age, Margaret Thatcher approached the queen.

The former prime minister, who is rarely seen in public anymore, curtsied as deeply as her legs would allow. The Iron Lady, outranked but not overshadowed, then led her queen, and Prince Philip, into the Mandarin Oriental hotel to join 680 other A-plus-list guests for a glitzy cocktail party to celebrate Thatcher's 80th birthday -- a milestone she reached six months before the woman who has reigned in Britain since 1953.

The evening was a celebration of Britain's first female prime minister, who dominated as much as led Britain from 1979 to 1990. Prime Minister Tony Blair was there, representing the leftish end of the guest list's broad political spectrum, with John Bolton, the U.S. ambassador to the United Nations, anchoring the rightward end. In between were the glitterati of British politics, industry, sports and show business: Andrew Lloyd Webber, Tim Rice and Joan Collins, and more lords and ladies and chauffeur-driven Rolls-Royces and Jaguars than might be found during a whole season on the polo circuit.

"It was a very happy occasion," said guest William Shawcross, a noted writer and broadcaster in Britain.

After years of making speeches around the world, and writing two books about her life, Thatcher retreated from public life on her doctor's orders in 2002 following a couple of small strokes that softened her famous steely demeanor and left her short-term memory gauzy.

Shawcross, interviewed after the party, said Thatcher gave a sharp three- or four-minute speech in response to a tribute by Peter Carrington, her former foreign minister. Shawcross said she thanked those who had worked with her during her years as prime minister, and said: "We didn't do everything we wanted to do. We wish we could have done more."

Gilly Penrose, spokesman for the Margaret Thatcher Foundation, said that despite the effects of the strokes, Thatcher stays active and interested in politics and current affairs. As a former prime minister, she holds a seat in the House of Lords, and Penrose said she attends sessions a couple of times a week -- including Wednesday's session.

"We have to pace what we do, but she's in good shape," Penrose said. "It's a jolly good age to reach, isn't it?"

Thatcher's husband of 51 years, Denis Thatcher, died in 2003.

"It was a sad blow to her when Denis passed away; that left her rather more lonely," said Charles Powell, who served for years as her private secretary and a chief adviser and still dines with her every couple of weeks. "She never really had a lot of friends. I suppose that is true of many prime ministers. They strive so hard to reach the top, they don't have time to pick up a lot of good friends along the way."

Powell remains a fierce guardian of her legacy. He calls her one of Britain's greatest prime ministers and insists that the economic prosperity Britain enjoys today has its foundations in the painful economic restructuring she oversaw.

"She is not the lady she was, but she is still vigorous and interested," Powell said. "The combative spirit is still there. She can still erupt magnificently over certain things. A Thatcher eruption was always a magnificent thing to behold, except if you were on the receiving end of the handbag."

Thatcher's last turn in the global spotlight was in June 2004 at Washington National Cathedral, at the funeral of her old friend Ronald Reagan.

Thatcher served as prime minister for 11 years, 6 months and 26 days, long enough to transform Britain and to create a world view in her name. Thatcherism was a tough-love vision of small government, free enterprise, individual responsibility and a bare-knuckle national security policy based on unambiguous rejection of Soviet communism -- a philosophy that endeared her to her ideological soul mate across the Atlantic.

As allies and dear friends, Thatcher and Reagan dominated an era, presiding over a decade that culminated with the fall of the Berlin Wall. They were revered as visionaries and reviled as class dividers -- one of Thatcher's and Reagan's harshest critics among Britain's intellectual "chattering classes" was Harold Pinter, the playwright who won the Nobel Prize for Literature on Thursday. Reagan survived an assassin's bullet, and Thatcher narrowly escaped an Irish Republican Army bomb in 1984 that killed five people.

So it surprised no one when she made a rare trip abroad to attend Reagan's service. Draped in a black veil, she sat two rows behind Nancy Reagan and next to former Soviet leader Mikhail Gorbachev, the man she once famously declared that she could "do business" with. Her touching eulogy to Reagan was delivered on a video screen as she sat silently in her pew.

Nancy Reagan was invited to Thursday's party, Penrose explained, but declined because she is busy with this month's opening of the Air Force One Pavilion at the Reagan Library in California. Gorbachev also declined, but he plans to visit Thatcher next week, as does her old friend Henry Kissinger. The Reagan administration was represented at the party by former defense secretary Caspar Weinberger, now using a wheelchair.

Thatcher's twin children, Mark and Carol, were also to attend the party. Mark Thatcher, 52, pleaded guilty in a South African court earlier this year to unwittingly helping to finance a coup plot in Equatorial Guinea in West Africa. (He was given a four-year suspended sentence and fined $506,000.)

Thatcher has long ceased to be an active player in British politics. But James Naughtie, who hosts BBC Radio 4's influential "Today" program, said it is only now, 15 years after she left office, that Thatcher's influence is finally fading from her Conservative Party. After the relatively lackluster years of Thatcher's successor, John Major -- who also attended the party -- the Tories have lost three straight elections since 1997 to Blair's Labor Party.

Naughtie said the Tories have failed in part because their reverence for Thatcher has hindered them from moving on and creating a "new era" to counter Blair and Labor. "Her 80th birthday coincides with her party getting out from under her at last."

Naughtie said one of the candidates for the party leadership recently described his platform as "Thatcherism with a social conscience," an implicit criticism of Thatcher that Naughtie said would have been considered heresy until recently. "It's like time, having stopped for many of the party leaders for 15 years, is finally moving forward again," he said.

Charles Moore, a former editor of the Telegraph who is writing a two-volume authorized biography of Thatcher, said she was angry and upset for several years after the Tories, facing heated criticism of an unpopular new tax scheme Thatcher had proposed, dumped her as prime minister in 1990.

"She'd won every election she'd fought and she was a world-famous prime minister, and they kicked her out -- suddenly all these people just put the knives in. She didn't understand it. But with greater age, she's become calmer and quieter."

But Moore said Thatcher is long past worrying about what political rivals might say.

"When you become a figure of history rather than current events, it doesn't matter whether people are for you or against you," Moore said. "The real point is, are they interested in you. And they are with her."

Powerhouse party: Queen Elizabeth, left, joined Margaret Thatcher for the former prime minister's 80th birthday.Tony and Cherie Blair, above, and Shirley Bassey, right, were among the A-plus-list guests attending the festivities for former British prime minister Margaret Thatcher at the Mandarin Oriental in London.