These small brown appointment diaries were kept in the Private Secretary's office, in the Prime Ministerial suite at Parliament House, during Harold Edward Holt's term as Prime Minister. A similar blue diary (A2588) was kept in the office of his Assistant Private Secretary. The diaries were used as a check against each other to avoid missed or conflicting appointments.

Entries in the diaries cover VIP visitors (including the Queen Mother, Lyndon B Johnson (President of the United States) and the Prime Ministers of Thailand, New Zealand, Japan, South Vietnam and Laos), meetings with Ministers, diplomats and others, Holt's VIP travel, Cabinet and Party meetings, House of Representatives sittings, press briefings, Premiers' Conferences, official and social engagements. The diaries were transferred to archival custody in December 1971.