Throughout his career, Penn explored illustration, advertising, photojournalism, portraiture, travel, still and television. Specialising in fashion photography, he worked almost exclusively in a studio environment. His subjects were set against a muted background and under specific lighting conditions, thus highlighting the qualities of the individual rather than their surroundings or social context. Penn’s portraits are stylistically often very simplistic, but the character of the sitter is always given great importance. His still-lives render flowers in exacting detail, highlighting their fragile beauty, while his series of cigarette butts monumentalise overlooked objects of detritus.

Penn published a number of critically acclaimed books such as Moments Preserved (1960) and Worlds in a Small Room (1974). His work has been exhibited in many galleries worldwide, famously exhibiting his photographs of Cigarettes in a 1975 exhibition at the Museum of Modern Art, New York and more recently a survey of his portraiture work at the National Portrait Gallery London, in 2010. Penn died in 2009.