Alexandra Halbert, who was working in a beer tent at the show, said she was about 200-300 yards away from the stage, with her back to it, when she heard “something that sounded like fireworks”.
“I turned around and the whole top part of the stage had collapsed, as well as the scaffolding,” she told the BBC.
“It seemed like there were a couple of minutes of hesitation and no one knew quite what to do. It was only afterwards that we all realised how serious it was.”
Johnson, also known for his work with the British pop band Keane, was interviewed while working at the V Festival with that band in 2009.