Butler won an international competition to design a monument to The Unknown Political Prisoner. The competition was intended to pay tribute to those who had been imprisoned or lost their lives in the cause of human freedom. Butler interpreted the theme specifically as being for 'a monument to those who had died in the concentration camps'. Had it ever been built it would have risen 300-400 feet high. It combines a rock foundation, three women 'in whose minds the unknown prisoner is remembered', and a tower to suggest 'the tyranny of persecution'. The original model was destroyed by a Hungarian refugee while on display at the Tate in 1953.