William John Kennedy moved to New York in the 1960s. He had a degree in fine art, but took jobs as a commercial photographer. On the side, he shot friends and acquaintances—including two guys who would become giants of Pop art but were just starting out, Robert Indiana and Andy Warhol. It was at Indiana’s first solo show, in 1962 at Stable Gallery, that Kennedy met the artist. Indiana later introduced Kennedy to Warhol, who was already running his Factory. Kennedy went on to photograph everyone in the world of Pop, from the writer Taylor Mead to the poet Gerard Malanga. He died in 2021. Now his New York pictures are on view in his former home in central London. —Elena Clavarino