Royal role

At a reception earlier in the day, the queen spelled out the role played by her family after the Olympics were revived in Athens in 1896.

"This will be the third London Olympiad. My great grandfather opened the 1908 Games at White City. My father opened the 1948 Games at Wembley Stadium. And, later this evening, I will take pleasure in declaring open the 2012 London Olympic Games at Stratford in the east of London," she said.

"Over recent months, many in these islands have watched with growing excitement the journey of the Olympic torch around the United Kingdom. As the torch has passed through villages and towns, it has drawn people together as families and communities.

"To me, this spirit of togetherness is a most important part of the Olympic ideal. And the British people can be proud of the part they have played in keeping the spirit alive."

The opening show, costing an estimated 27 million pounds ($42 million), was inspired by William Shakespeare's play "The Tempest", his late-life meditation on age and mortality.

Children were centre-stage throughout, starting from the moment when live pictures of junior choirs singing in the landscapes of England, Scotland, Wales and Northern Ireland were beamed into the stadium's giant screens, four traditional songs woven together into a musical tapestry of Britain.

Oscar-winning film director Danny Boyle began his sweep through British history by grassing over the arena in a depiction of the pastoral idyll mythologised by the romantic poet William Blake as "England's green and pleasant land".

Idyll turned swiftly to inferno as the Industrial Revolution's "dark Satanic mills" burst from the ground, before those same mills forged the last of five giant rings that interlocked and were carried aloft by balloons.

Many sequences turned the entire stadium into a vast video screen made up of tens of thousands of "pixels" attached to the seats. One giant message, unveiled by Tim Berners-Lee, British inventor of the world wide web, read "This is for Everyone".

The performance included surreal and often humorous references to British achievements, especially in social reform and the arts, and was due to conclude with a performance by former Beatle Paul McCartney.

Until the last few days, media coverage had been dominated by security firm G4S's admission that it could not provide enough guards for Olympic venues. Thousands of extra soldiers had to be deployed at the last minute, despite the company's multi-million-dollar contract from the government.

Counter-terrorism chiefs have played down fears of a major attack on the Games, and Prime Minister David Cameron said that a safe and secure Olympics was his priority.

Suicide attacks on London on July 7, 2005, the day after London was awarded the Games, killed 52 people. This year the Games will mark the 40th anniversary of the 1972 Munich massacre, when 11 Israeli Olympic team members were killed by Palestinian militants.

"This is the biggest security operation in our peacetime history, bar none," Cameron said, "and we are leaving nothing to chance."