Hayward Gallery; Tate Britain, London The riveting street photography of Diane Arbus is an intense, two-way exchange, while Don McCullin’s urgent lifetime’s work amounts to a history of our times It is 1957, and a girl clutching schoolbooks to her small body steps from the gutter to the sidewalk of an empty New York street. She is getting home on her own, native wit condensed in her determined face. Sun gilds the distant buildings, but she seems to live in a foreground of grimy shadows – young and yet prematurely old, the pompom on her hat a frivolous betrayal of her toughness. She shoots a dark glance at the photographer. Diane Arbus (1923-71) saw the street as a land of secrets, each passing figure properly mysterious. Roaming about with her old 35mm camera, she shows New Yorkers exactly this way. A woman in costly furs stares back at her, startled, barely holding herself together. A young mother carrying her child appears as grave as the Madonna in a Pietà. And a transfixing image of a taxi waiting at the lights is a miniature travelling theatre. Inside, the almost illegible figure of a man turns away from his female companion, who is furiously biting her nails as she smokes. The driver, noticing Arbus, seems equally bemused by the photographer outside, crouching down with her lens, and the tension inside his vehicle. This image, one of a hundred in the Hayward’s tremendous exhibition, was only discovered after Arbus’s suicide at 48. It comes from a cache of unpublished photographs begun in the late 1950s, the start of her independent career after a decade working with her husband, and before the classic photographs that made her one of the great names of American art. To describe these images as a revelation would be true, but mere understatement. Many have never been shown here before. What they give is the strongest sense of Arbus as a lone soul out in the city, fixing upon the strangeness everywhere around her with a fierce and yet empathetic eye.