Looking out over the audience at the Crystal Palace Bowl, Nas feels moved to reminisce about his first visit to London. Before Nas appears at the festival’s first London iteration, the Roots play their own set, augmented by a guest appearance from Common. View image in fullscreen Photograph: Dave Burke/ShutterstockWhen Nas takes the stage, the exuberant mood shifts. His set acts like a career retrospective albeit one noticeably bigger on 90s classics – NY State of Mind, Hate Me Now – than more recent material. Behind him, the screens show old photos from the same era as his first London visit, baby-faced, sitting outside the Queensbridge projects.