Expo 67 did not get off to a smooth start; in 1963, many top organizing committee officials resigned. The main reason for the resignations was Mayor Drapeau's choice of the site on new islands to be created around the existing St. Helen's Island and also that a computer program predicted that the event could not possibly be constructed in time. Another more likely reason for the mass resignations was that on April 22, 1963, the federal Liberal government of Prime Minister Lester Pearson took power. This meant that former Prime Minister John Diefenbaker's Progressive Conservative government appointees to the board of directors of the Canadian Corporation for the 1967 World Exhibition were likely forced to resign.