LONDON: The eagerly awaited opening ceremony to the 2012 Olympic Games kicked off on Friday with a mass countdown and the chime of a giant bell, ushering in an eccentric and exuberant celebration of British history, art and culture.

Some 60,000 spectators crowded into the state-of-the-art arena at the Olympic Park, built in a previously run-down area of the city's East End, and over a billion more people tuned in around the world for the three-hour extravaganza.

The centre of the stadium was transformed into an English pastoral idyll complete with grassy meadows, fences, hedges, a water mill, maypoles and even a cottage with smoking chimney.

A cast including shepherdesses, sheep, geese, dogs and a village cricket team filled the stage during the one-hour prologue to the show that included a dramatic, low-level fly-past by the jets of the Royal Air Force's Red Arrows stunt team.

At one end of the stadium stands a grassy knoll topped by a tree and at the other end the bell. In front of each is a “mosh pit” of people conjuring the spirit of the Glastonbury music festival and Last Night of the Proms classical concert.

London Mayor Boris Johnson sought to sum up the mood of excitement sweeping the capital.

“The excitement is growing so much I think the Geiger counter of Olympo-mania is going to go zoink off the scale,” he told crowds at Hyde Park in the city centre.

Among the crowd were celebrities, ordinary Londoners, visitors from abroad and dignitaries including US First Lady Michelle Obama as well as presidents, prime ministers and European royalty.

At the end of the event, which also includes speeches, the athletes' parade and the lighting of the Olympic cauldron, Queen Elizabeth, celebrating her Diamond Jubilee this year, declares the 2012 Games open.

Over the following 17 days, the drama of sporting contest takes hold as more than 16,000 athletes from 204 countries will aim to achieve their ultimate dream - Olympic gold.

Oscar-winning “Slumdog Millionaire” director Danny Boyle has masterminded the show, costing 27 million pounds ($42 million) to stage, less than half the estimated spending on the Beijing equivalent in 2008 and dramatically different in style.

The ceremony opened with a countdown followed by a chime of an especially cast, 23-tonne Olympic bell which was rung by Britain's Tour de France winner Bradley Wiggins.

“ISLE OF WONDER”

Boyle's colourful and sometimes chaotic vision aims to create a kaleidoscope of what it means to be British, an approach that could appeal to the home audience but leave many foreign viewers scratching their heads at times.

Entitled “Isles of Wonder” and inspired by Shakespeare's “The Tempest”, the show takes viewers on a journey from what poet William Blake famously called “England's green and pleasant land” to the “dark Satanic mills” of the Industrial Revolution.

Divided into three main sections, it will also celebrate the National Health Service, cherished by Britons despite being a political hot potato at a time when austerity measures have forced major spending cuts.

It includes a moment's silence to those who fell in conflict, spectacular light effects generated by coloured “pixel” light boxes beside each seat and giant puppets of some of the most famous characters from children's literature.

Spectators will be urged to join in traditional sing-a-longs, beloved by East End pub-drinkers, and help to create spectacular visual effects at an event that sets the tone for the sporting spectacle.

Boyle has conceded that audiences overseas may be confused.

“In the second half of it you'll see what we call the industrial parade which is actually slightly surreal, some of you will be baffled, I can guarantee it,” he told reporters.

He also paid tribute to the 10,000 volunteers, cast and crew taking part in the ceremony.

“We hope the feeling of the show is a celebration of generosity,” he said. “There's no better expression of that than these volunteers.”

Chinese reporters at the stadium asked British colleagues what the various stages meant, saying they were struggling to understand the concepts. “It's really difficult to explain this to Chinese readers,” one said.

Boyle has been at pains to encourage volunteers taking part in the show and tens of thousands more who attended rehearsals this week to keep its content a surprise.

That has not prevented details being leaked through Twitter, Facebook and the mainstream media.

Ex-Beatle Paul McCartney will be among the many performers on the night, but the biggest secret of all - who has the honour of lighting the Olympic cauldron at the end of the show - remains a mystery.