Later in the afternoon, William and Middleton delighted the crowds outside of Buckingham Palace by going out for a spin in a dark-blue Aston Martin Volante convertible festooned with ribbons, bows and balloons and bearing the ceremonial license plate "JU5T WED."

It drove down London's Mall for a couple minutes before pulling in to Clarence House, drawing cheers from the lingering crowd.

The Aston Martin has been owned since 1969 by Prince Charles, an ardent environmentalist who had the car converted so that it could run on bioethanol made from the waste matter generated by English wine production.

It was accompanied by a search-and-rescue helicopter in a special flyby. William is a serving search-and-rescue pilot on the island of Anglesey in Wales.

The palace was holding two parties, one hosted by the queen for 650 guests, and an evening dinner dance for 300 close friends. The queen and her husband have promised to go away for the evening, leaving the younger royals free to party the night away-- and Harry to make his best man's speech away from his grandparents' ears.

British singer Ellie Goulding, 24, is reportedly going to perform, and rumors have it that Harry has even planned a breakfast for those with the stamina to dance all night.

Plumage of Amazonian variety filled the cavernous abbey as some 1,900 guests filed in, the vast majority of women in hats, some a full two feet (half a meter) across or high. Several looked like dinner plates, and one woman wore a bright red fascinator that resembled a flame licking her cheek. A BBC commentator noted there were some "very odd (fashion) choices" walking through the abbey door.

Most men, however, looked elegant and suave in long tails, some highlighted by formal plaid pants and vests. Others wore military uniforms.

The queen, of course, wore a soft yellow hat and coat dress, just like the bookies had predicted.

All the details -- the wedding dress, her hair, their titles, the romantic kiss on the balcony, the honeymoon -- were finally being answered. But the biggest question won't be resolved for years: Will this royal couple live happily ever after?

Will their union endure like that of William's grandparents -- Queen Elizabeth II and Prince Philip, now in its 64th year -- or crumble in a spectacular and mortifying fashion like that of his own parents, Prince Charles and Princess Diana?

Recent history augurs badly: The first marriages of three of the queen's four children ended in divorce. But William and Kate seem to glow with happiness in each other's company, and unlike Charles and Diana they've had eight years to figure out that they want to be together.

Still, the fate of their marriage depends on private matters impossible for the public to gauge, since any wedding is fundamentally about two people. Will their lives together, starting with such high hopes, be blessed by good fortune, children, good health, productive work?

Much will depend on whether 28-year-old William and 29-year-old Kate can summon the things every couple needs: patience, love, wit and wisdom. But they face the twin burdens of fame and scrutiny. Money, power, beauty -- it can all go wrong if not carefully nurtured.

These are the thorny issues upon which the fate of the monarchy rests, as the remarkable queen, now 85, inevitably ages and declines.

Hundreds of street parties were under way as Britons celebrated the heritage that makes them unique -- and overseas visitors came to witness those traditions.

Brenda Hunt-Stevenson, a 56-year-old retired teacher from Newfoundland, Canada, said there was only one thing on her mind. "I want to see that kiss on that balcony. That's going to clinch it for me. I don't care what Kate wears. She is beautiful anyway."

The celebration was British to the core, from the freshly polished horse-drawn carriages to the sausages and lager served at street parties. Some pubs opened early in the morning, offering beer and English breakfasts -- sausages, beans, toast, fried eggs and bacon.

Police said they had arrested 43 people for offenses including drunkenness, breach of peace, and theft.

The festivities reflected Britons' continuing fascination with the royal family, which despite its foibles remains a powerful symbol of unity and pride.

"It's very exciting," Prime Minister David Cameron said. "I went on to the mall last night and met some people sleeping on the streets. There's a sense of excitement that you can't really put a word to ... it's a chance to celebrate."

Others disagreed.

John Deery, 45, from west London, described the royal family as "unjustifiable" in the modern day and age.

"What I want is a democratic alternative to the monarchy," he said.

A number of famous people were left off the guest list, including President Barack Obama and Britain's last two prime ministers, Tony Blair and Gordon Brown of the Labour Party, which is not as strong a backer of the monarchy as the governing Conservatives. Some critics call that a snub which could resonate for years among Labour voters.