UPDATED 7 P.M.
Britain's Queen Elizabeth II this afternoon sailed on a royal barge at the centre of a spectacular 1,000-boat river pageant on the River Thames, the set-piece of celebrations to mark her diamond jubilee.
The Queen travelled down the river on the red-and-gold Spirit of Chartwell with hundreds of kayaks, steamers and tugs in front and behind the ceremonial barge.
The banks of the Thames were thronged with hundreds of thousands of spectators waving Union Jack flags.
Heavy rain which had fallen in the morning cleared for the start of the pageant before returning later, though it had no effect on the enthusiasm of the cheering crowds.
Street parties were held around the country to mark the 60th year of the queen's reign, with some moving the festivities inside when the weather changed.
Earlier, the heir to the throne Prince Charles and his wife Camilla dropped in on one street party in Piccadilly in central London and sat at a table draped in a Union Jack, chatting with residents.
The biggest event on the Thames for 350 years started with the ringing of eight Jubilee bells on a barge and ended in the early evening when the last boats complete the 11-kilometre (seven-mile) journey.
The Queen, dressed in a white hat and a silver and white coat and dress designed by Angela Kelly, was ferried to the barge on the launch of the Royal Yacht Britannia, the ship she dearly loved which was decommissioned in 1997.
Waiting for the queen on the barge were senior royals including Prince William and his wife Catherine, who wore a vivid red dress by Alexander McQueen, the same designer who created her wedding gown.
Spectators lining the banks of the Thames roared when the royal barge came into sight.
"The atmosphere was brilliant, everyone seemed in a good mood. The queen's boat was beautiful, really colourful, and Kate looked lovely in red," said Barbara Barke, a pensioner from Essex, eastern England.
Behind the queen's barge was massed a flotilla of speedboats, firefighting tugs and historic vessels, including Dunkirk "little ships" that evacuated British forces from continental Europe in World War II.
The armada was led by the barge carrying the bells, then Gloriana, which was rowed by quadruple Olympic gold medallist Steve Redgrave alongside injured servicemen.
The procession of boats stretched as far as the eye could see.
"It's glorious. It's a momentous occasion. It makes you proud to be a Brit," said Neil Munn, who works in advertising and watched the pageant with his wife and four daughters.
"We're here to salute the queen after 60 years' hard work."
The celebrations come as the royal family enjoys its highest support for decades. That is especially true for the queen, who is only the second British monarch to celebrate a diamond jubilee, after Queen Victoria in 1897.
Several hundred anti-monarchist protesters were booed and had their chants drowned out with renditions of "God Save The Queen" as they staged a demonstration.
The members of the campaign group Republic waved placards declaring "Citizens, not subjects", "We want a vote, not a boat" and "Don't jubilee've it".
But their numbers were dwarfed by the hundreds of thousands who turned out to see the show.
Some diehard royal fans camped out overnight along the Thames and braved the rain which fell for much of the night to secure a good vantage point.
Nicola Holder, a retired community worker from Devon in southwest England, had put up with "miserable" weather to spend the night on Westminster Bridge.
"I've never seen anything like this, and I've just got so much respect for the queen," she told AFP.
"I can't think of any other human being who's set an example like she has. I think she's been a very wise lady -- as a nation we owe her a huge debt."
The river pageant - which ended with fireworks from Tower Bridge - was the highpoint of four days of national celebrations, which began yesterday when the queen attended the Epsom Derby horse race, where she was greeted by flag-waving crowds.
Tomorrow, a concert takes place in the shadow of Buckingham Palace featuring Beatles star Paul McCartney and other top names, before the festivities culminate in the pomp and splendour of a ceremonial parade on Tuesday.
