London mayor left hanging in Olympic zipwire mishap, London Mayor Boris Johnson, tipped as a possible future British prime minister, made a striking entry to an Olympic event by zipwire Wednesday -- only to get stuck dangling over the crowd.Waving a Union Jack flag in each hand, the colourful Conservative mayor initially gathered some speed as he flew over Victoria Park in east London, where the Games were being shown on giant screens."Is it a bird? Is it a plane?" an announcer said as the mayor waved to the crowds below, wearing a bright blue helmet with his smart business suit.But he ground to a halt halfway across the 320-metre (350-yard) zipwire -- which is also open to the public -- and was left hanging awkwardly over the spectators, still wielding his flags."Can you get me a rope? Get me a rope, ok?" he called to the crowds. "I think we need to test it on somebody going a bit faster..."Onlookers said he was left hanging for several minutes, before officials pulled him the rest of the way."I think possibly what had happened was that they left a brake on or something," Johnson told ITV television once he was back on the ground."But anyway, it was wonderful and I thoroughly recommend it."