The British Empire, once the planet’s stiff-upper-lipped conqueror, now must call on the bumbling comic sociopath Mr. Bean as its emissary to the world. Judging from the Opening Ceremonies of the 2012 Summer Olympics, the starchy United Kingdom has become a pop-culture commonwealth of verdant isles known best for germinating Harry Potter, David Beckham and, of course, the squeezable corgis that loll about Buckingham Palace.

The Opening Ceremonies allow a host country both to dramatize its essence and acknowledge the world’s perception of it. On Friday night, Britain produced a splattered, rollicking, three-hour-plus event that rendered itself in stark contrast to China four years ago: The home of the 2012 Games knows how to have a good time, tingle one’s spine and elicit groans — sometimes simultaneously.

Beijing’s Opening Ceremonies were heralded by 2,008 drummers walloping their instruments with stunning, militaristic precision. London’s started on a pasture with livestock.

Then the queen parachuted out of a helicopter with James Bond.

That was the intended effect, anyway, of a short film featuring the royal corgis, Queen Elizabeth II (in her first acting role) and her unlikely buddy, current Bond interpreter Daniel Craig. The film ended with QE2 and 007 ready to jump, just as a real-life copter appeared over the 65,000 attendees at the Olympic Stadium. A less geriatric stand-in for the sovereign presumably plummeted forth, a Union Jack parachute deploying behind. Then the real queen, poker-faced as always, entered her box seat with a wave.

Casting her majesty as the latest Bond girl was a bit of a coup, and a stroke of genius, from Ceremonies director Danny Boyle, the British filmmaker best known for “Slumdog Millionaire.” Boyle conjured his trademark magical realism to tell Britain’s story in theater, dance, film and pyrotechnics — a spectacle drawing on the cinematic aerobics of an Oscars telecast and the boom-boom choreography of a Super Bowl halftime show. It was stunning and stirring at its beginning and end, and a kinetic, bloody mess in between, hampered further by NBC’s self-promotional commercial breaks, which fractured continuity and stalled momentum.

The pasture set piece, featuring real sod and real hay and real sheep, was a stage for a British history lesson overseen by a top-hatted Kenneth Branagh, who quoted lines from Shakespeare’s “The Tempest” in a nod to its island setting, which inspired Boyle’s schematic of “isles of wonder,” i.e. the British Isles. (Get it?) In the Ceremonies’ most audacious segment, the pasture transformed into a smelting factory to show Britain’s transition from an agrarian society to an industrial one. Towering smokestacks rose from the ground and a river of fake molten steel flowed to form a glowing Olympic ring, which ascended to the sky as four more rings flew in from the edges of the stadium to form the Games’ logo. The effect was stunning and unified.

Then things got slapdash. Nurses pushed children on trampoline beds into the stadium to celebrate Britain’s National Health Service. (Hey, Mitt! Britain will take your thoughts on socialized medicine now.) The great villains of children’s literature, led by a 100-foot puppet of Lord Voldemort, spooked the children, only to be vanquished by an equally terrifying swarm of Mary Poppinses that descended by umbrellas from the sky. The media-shy “Harry Potter” author J.K. Rowling read a few lines from “Peter Pan,” and then Rowan Atkinson, exhuming his Mr. Bean character for the evening’s cheekiest non sequitur, “played” the synthesizer on “Chariots of Fire” with the London Symphony Orchestra. At one point, soccer superstar Beckham was shown ferrying the torch by motorboat up the Thames.

NBC, hewing to history, staged its own revolution against the Brits by deploying Matt Lauer and Meredith Vieira, whose unctuous scripted lines and painful ad-libs soured moment after moment.

“I’m telling you, this is like the soundtrack of my life,” Vieira said during an interminable segment on Britain’s digital age, featuring a horde of teenagers texting on their smartphones as they danced to the Beatles, the Kinks and the Who. Vieira started to sing, but was swiftly shushed by Lauer.

Like any Opening Ceremonies, the spectacle switches to pageantry at a certain point to accommodate the athletes (remember them?). The teams of 205 nations paraded their way through in alphabetical order, as Lauer and Bob Costas traded high-school trivia with each other (“Tajikistan now, a mountainous former Soviet republic . . . Tanzania, home to the iconic Mount Kilimanjaro . . .”).

Pageantry rarely makes for good television, but it does give us an opportunity to judge our global companions for their country’s fashion sense. Although, shall we start with our own? Yanks in berets? Ralph Lauren’s citizenship should be revoked. The Italians looked much more comfortable and classy in their Giorgio Armani. Even the Canadians’ windbreaker-khakis combination would have been better.

Of course, the Opening Ceremonies occurred in London several hours before they were edited and broadcast stateside in primetime, although anyone with an Internet connection and a brain could have found a passable live stream — and traded Lauer and Vieira for a slightly longer run time (worth it).

After the Ceremonies’ loud, thumpy middle — in which every conceivable scrap of British culture, from Monty Python to the Eurythmics, was thrown into a montage or dance — Boyle righted the ship with a gorgeous torch-lighting sparked by champion rower Sir Steve Redgrave. Dozens of scattered copper petals, each carrying a smaller flame, ascended from the well-trod pasture to form a tighter constellation in the sky, punctuated by a cacophonous fireworks display accompanied by Pink Floyd’s “Eclipse.” The imagery was classic. The musical choice was a bit rebellious. The moment worked beautifully.

Then the only bit of Britain yet to appear did: Sir Paul McCartney led the stadium in chorus after chorus of “Hey Jude,” a rousing and repetitive conclusion to a rousing and erratic Opening Ceremonies.