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With tens of thousands of athletes and fans in attendance and a projected four billion spectators expected to watch on TV, the London Games officially kicked off Friday night with a celebration at the Olympic Stadium.

The rain stayed away until minutes before the start of the opening ceremony, when it began to fall lightly before going away.

Many details of the ceremony leaked days and weeks beforehand, but the always well-guarded secret of who will light the Olympic cauldron remained a mystery as the celebration began.

Roger Bannister, the first person to run a sub 4-minute mile, and five-time Olympic champion rower Steve Redgrave were considered the favorites.

The ceremony, overseen by Academy Award-winning film director Danny Boyle, features appearances by Queen Elizabeth II and Paul McCartney, who leads a sing-along to the Beatles standard "Hey Jude" at the end.

The latest James Bond, Daniel Craig, is also involved and Harry Potter author J.K. Rowling was to read the opening paragraph of J.M. Barrie's Peter Pan.

There are many elements common to Olympic ceremonies, including music and choreography. British music, of course, plays a big part. Pink Floyd's "Time," Sex Pistols' "God Save the Queen" and The Clash's "London Calling" are on the set list.

Gray clouds appeared overhead hours before the start of the ceremony, a breeze picked up and the temperature cooled, but it hadn't rained by the time jets buzzed the stadium trailing red, white and blue smoke.

Instead, a passing shower hit as the crowd was being warmed up. It drizzled a bit later just as the ceremony was about to begin.

London had big shoes to fill. Beijing's grand spectacle four years ago is generally considered to have set a new standard for Olympic ceremonies.

Even Jacques Rogge, the outgoing IOC president presiding over his last games, said London would do well not to try to emulate the 2008 ceremony.

The theme Friday -- "This is for everyone" -- was based on what computer scientist and Londoner Tim Berners-Lee said after inventing the World Wide Web and was meant to celebrate the achievements of key British figures and the British people.

The stadium's centerpiece was a replica of a British meadow, complete with a water wheel and cottage and almost 80,000 square feet of real turf. Actors wearing pastoral costumes played soccer on the field before the ceremony officially began.

U.S. athletes were to wear the controversial ceremony gear made in China. They are led into the stadium by flag bearer Mariel Zagunis, a fencer. As usual, some were skipping the ceremony.

Canada's flag bearer is Simon Whitfield, who won the first-ever Olympic triathlon gold medal in 2000. Leading host Great Britain in the parade of athletes is multiple gold medalist Chris Hoy, who is the first cyclist to ever carry a country's flag in an opening ceremony.

Athletes enter the stadium in alphabetical order by country, except for Greece, which traditionally leads the procession, and Great Britain, which goes last as the host nation.

Other dignitaries in attendance included U.S. first lady Michelle Obama and Mitt Romney, the Republican presidential challenger.

The ceremony was not to include a moment of silence to mark 40 years since the killing of 11 Israeli athletes by Palestinian guerrillas at the 1972 Munich Olympics.

The London Games will conclude in 16 days with the closing ceremony on Sunday, Aug. 12.