The sky's the limit.
At the climax of his three-hour set, Springsteen and McCartney, backed by the E Street Band and Rage Against the Machine guitarist Tom Morello, played a storming rendition of "I Saw Her Standing There" to a rapturous crowd. Springsteen's delight was palpable: He grinned throughout, his face lit up like a child with a super-sized Christmas gift.
The supergroup then segued into a sizzling version of "Twist and Shout" -- but as the night peaked against a backdrop of fireworks, a drably dressed man with sensible hair could be seen waving frantically at the back of the stage, indicating the rock legends' time was drawing to a close.
Then, at 10:40 p.m. local time, as Springsteen and McCartney were winding up the extended "Twist and Shout," the sound suddenly dampened, and went quiet....London's Westminster Council later confirmed that concert organizers Hard Rock Calling had cut the power, saying they "were sticking to their license for the event." According to the Hard Rock Calling website, Springsteen had been due to finish his set at 10:15 p.m.