After supporting Prime Minister Anthony Eden during the 1956 invasion of Suez, Ridsdale served from 1957 to 1958 as the Parliamentary Private Secretary (PPS) to John Profumo, the Parliamentary Under-Secretary of State for the Colonies. From 1958 to 1960 he was PPS to the Minister of State for Foreign Affairs. His ministerial career was brief, as Parliamentary Under-Secretary of State for Air from 1962 to 1964.