The art world has spawned many original individuals, but few are quite as unlikely as Corita Kent, the Pop Art nun. In the 1960s heyday of the movement, Sr Corita, along with Andy Warhol and Robert Rauschenberg, was at its cutting edge, producing a prolific range of vibrant silkscreens that capture the twin ambitions of the time: to tap into popular culture, and to harness public opinion on civil rights, the Vietnam War and nuclear proliferation.