LONDON — Cold weather and the threat of rain did nothing to deter thousands of people from pouring into Hyde Park Friday to celebrate the marriage of Prince William to Catherine Middleton in true British style.
Some 300,000 gathered, waving Union Jack flags and bottles of champagne, as they spread out picnics on the grass in front of three massive television screens broadcasting the royal wedding.
Fancy dress prevailed. Women wore wedding gowns, Union Jack miniskirts, tiaras, Union Jack face-paint and T-shirts emblazoned with “It should have been me.”
Some men also wore wedding gowns, as well as Union Jack trousers, morning suits, wigs, top hats and crowns of every description. Four men wore T-shirts that read “I [heart] Willy.”
The party started early. By 7:30 a.m., nearly a thousand already had staked out their patches and popped open the champagne.
Among the first to arrive was a group of four young people in formal dresses, hats and suits, who laid out an elegant spread of tea cakes and sandwiches.
“We were hoping to get into Westminster Abbey,” said Tim Huxtable, 32, of Clapham. “Maybe there were a few last-minute dropouts? But seriously, we just wanted to celebrate with our friends.”
“It’s a great British party, and we just wanted to be part of it,” said James Thompson, 27, of Islington.
Foreigners enjoyed the spectacle as well.
“I’m very, very excited,” said Taleb Yarah, 45, of Iraq, sporting a gold paper crown. “This is something wow, something I never saw before. I am happy to be free in my second home and to share the happiness.”
Mr. Yarah, a counselor with the British National Health Service, was celebrating with a group of similarly crowned friends who work for British Airways.
Still, the event seemed to be as least as much about celebrating Britishness as it was about the wedding itself.
“It’s nice to feel British, to have a sense of belonging,” said Charlie Saunders, 22, of Chipperfield, dressed as a royal guard. “And it’s lovely to be included in a day that will go down in history.”
That desire to take part in history was a major draw.
“Our own children and grandchildren will learn about this in years to come,” said Toni Pearce, 57, a teacher from Southampton. “It’s a part of history.”
She came with eight other women, all dressed in pink jackets and wearing tiaras and pink feathers in their hair as they breakfasted on champagne and fairy cakes served on royal wedding-themed paper plates. The women have been traveling together for 15 years.
Katrina Stone, whose 51st birthday the women also were celebrating, said she remembered seeing Princess Diana on her honeymoon in Romsey, and was excited to honor her by celebrating the marriage of her son.
Many foreigners said they loved that the U.K. kept its royal traditions alive.
“It’s a pleasure to me that the English are still holding on to traditions, which keep the country together,” said Helena Mysko, 63, formerly of Germany. “I am British now,” she added, “and so proud!”
Mina Kuchuk, 66, of Moldavia, who moved to London to study English, stood close to the front of the crowd, staring up at the screen with tears in her eyes.
“I never saw something like this in my life,” she said, her voice cracking with emotion. “I think only England could organize this event. Thank God, who brought me to this place.”
It’s critical to preserve traditions for future generations, she added. “Many countries forget this. Look at the Soviet Union.”
Canadians were also out in force, many wrapped in Canadian flags. “We’re excited,” said Michael Larocque, 35, of Winnipeg. “She’s our queen, too.”
The crowd erupted in cheers when Prince William’s car emerged from Clarence House, when Queen Elizabeth II arrived at Westminster Abbey and when Catherine Middleton gave them a first glimpse of her dress.
But when the ceremony began, the thousands of celebrants fell silent, and remained rapt throughout. Just about everyone interviewed had the same response: “It was beautiful.”
The ceremony was followed by frenetic flag-waving, toasts to the royal couple, and animated dancing, kicked off by Aerosmith’s hit song “I Don’t Want to Miss a Thing.”
The festivities were expected to carry on until late Friday.
“I’ll be clearing up until the last person goes home, around 10 or 11,” said Karen Dumble, 36, of Hackney, who was picking up trash for the city.
But she isn’t complaining. “I chose to be here. It’s a nice atmosphere.”
A half-hour walk across town, a much smaller crowd gathered for a different sort of party — a “Not the royal wedding street party” sponsored by anti-monarchy group Republic.
It was a quieter affair, but the celebrants, many wearing T-shirts, reading “Citizen, not subject,” spoke with just as much passion about their vision of a Republican Britain.
“What is being exported all over the world is the worst of Britain, a celebration of life chances allocated on birth rather than merit,” said Charles Keidan, 34, of Hamstead, who wore a T-shirt stating simply “Revolt.”
There shouldn’t be such an outpouring of support for the royal couple “just because they look nice,” he said.
Professional magician Sebastian Hunt, 38, of Cambridgeshire, said he wished the couple well. “It’s the public cost of the wedding I have darker feelings about.”
Republic’s Campaign Manager Graham Smith said he was happy with the turnout, which he estimated at between several hundred and a thousand throughout the day.
Back in Hyde Park, some said it wasn’t the monarchy they were celebrating but love and marriage.
“When you find love, it’s special,” said Bimpe Arowolo, 54, formerly of Nigeria but now a Londoner. “I love encouraging people who are in love.”