 Eden resigned in January 1957 . In 1955 he had been the obvious successor to Churchill , but this time there was no clear heir apparent . Leaders of the Conservative party were not elected by ballot of MPs or party members , but emerged after informal soundings within the party , known as " the customary processes of consultation " . The chief whip , Edward Heath , canvassed the views of backbench Conservative MPs , and two senior Conservative peers , the Lord President of the Council , Lord Salisbury , and the Lord Chancellor , Lord Kilmuir , saw members of the cabinet individually to ascertain their preferences . Only one cabinet colleague supported Butler ; the rest , including Home , opted for Macmillan . Churchill , whom the Queen consulted , did the same . Macmillan was appointed Prime Minister on 10 January 1957 . 
