The post war minutes followed the standard notation of a two-letter series indicator, the meeting number, the year and the conclusion or agenda item number. CM 12 (51)1 refers to the 12th meeting in 1951, and the first conclusion or agenda item. During this period the internal references were changed periodically. Care must be taken to ensure the correct meeting is identified in years where two different references are in use. For example, there are two 1 (51) meetings, one under the CM reference (for the Labour government under Attlee), and one for the CC reference (for the Conservative government under Churchill which took power later in 1951).
CM is used 1945-1951, 1955-1957, 1963-1964, 1970-1974, 1976-1979
CC is used 1951-1955, 1957-1963, 1964-1970, 1974-1976