Paul McCartney's Surprise Appearance at Bruce Springsteen Show Cut Short During UK Festival

NBC UniversalA historic rock moment was cut short Saturday night in London's Hyde Park, during a surprise guest appearance by Paul McCartney at Bruce Springsteen and the E Street Band's Hard Rock Calling festival set. After Sir Paul had performed the Beatles hits "I Saw Her Standing There" and "Twist and Shout" with The Boss as part of the show's encore, organizers cut power to the stage because the concert had gone passed the 10:30 p.m. curfew, drawing boos from the disappointed crowd.

According to BBC News, Live Nation reps issued a statement calling the stoppage of the "three hour plus" show "unfortunate," while explaining, "The curfew is laid down by the authorities in the interest of the public's health and safety."

Commenting on the incident during a radio interview, London's mayor, Boris Johnson, declared, "If they'd have called me, my answer would have been for them to jam in the name of the Lord."

E Street Band guitarist "Little Steven" Van Zandt, meanwhile, posted a series of messages on his Twitter account expressing his annoyance over the abbreviated event.

"One of the great gigs ever in my opinion," he wrote. "But seriously, when did England become a police state?...I'm sorry but I have to be honest I'm p**sed. Like I said, it didn't ruin the great night. But when I'm jamming with McCartney don't bug me!"

Van Zandt softened his remarks a bit in a later tweet, writing, "There's no grudges to be held. Just feel bad for our great fans. Hard Rock is cool. Live Nation is cool. It's some City Council stupid rule."

Springsteen and company's marathon show Saturday brought to an end the second day of the three-day Hard Rock Calling fest. Besides McCartney, The Boss also welcomed ex-Creedence Cleawater Revival frontman John Fogerty and Rage Against the Machine guitarist Tom Morello to the stage during the gig. Fogerty and Morello also played their own sets earlier that day.