Bob Gruen is the latest photographer to speak with Nick Knight in our series of interviews Punk: Photography. The pair speak about Gruen's shot of Sid Vicious on the Sex Pistols' American tour in 1978. His image captures a moment of extreme chaos, Sid scratched 'gimme a fix' on to his chest and had just been punched in the face by a female fan. Gruen watched from stage right, and gives a detailed account of the performance that night. The shot features in our current exhibition Photography of Punk at 19 Motcomb Street and the interview series continues this week when Dennis Morris recounts shooting John Lydon back stage at the Marquee Club in 1977.