In the last years of his life, King spent much time planning the writing of his memoirs. He intended his diary to be the main source for information.
In addition to the diary, source material for the memoirs included huge quantities of papers stored at Laurier House and in the East Block. In 1946, two people were hired to undertake the organization and classification of the documents: Fred Gibson of Kingston, Ontario, who was working on a doctorate at Harvard, and to assist him, Jacqueline Côté, an honours graduate of history from Queen's and a former student of Gibson. They were paid by the Public Archives of Canada.
The Rockefeller Foundation contributed $100,000 to assist in the writing of King's memoirs. King used some of this money to rehire Fred McGregor, who had been his Secretary in the early days.
Before he could begin the actual writing of his memoirs, King died in 1950. In his will, he named four literary executors: Fred McGregor, J.W. Pickersgill, Norman Robertson and Dominion Archivist Dr. W. Kaye Lamb. Among other things, he instructed them to "destroy all of my diaries except those parts which I have indicated are and shall be available for publication or use." But he never indicated the parts that were to be kept.
The diary was a monumental document to which he had devoted countless hours of his life, and since about 1935, several members of his staff had spent untold hours on it. He certainly intended it to be the basis for his biography. But there were also many personal sections which he clearly did not intend to be made public. The executors had to decide what to keep, and who should be allowed access to it.
King himself seems to have been ambivalent about how much of the diary should become open. There is some evidence that, from the beginning, he intended at least some portions to become part of the public record. On the very first page, he wrote that one of his reasons for keeping the diary was to enable "the reader...to trace how the author has sought to improve his time." (Diary, September 6, 1893) The impersonal wording implies that the reader would not be a close associate. King also gave verbal advice, toward the end of his life, that parts of the diary should be retained for use by his eventual biographers.
But many references in the diary indicate that he meant it to be absolutely confidential. For example, on the flyleaf of the 1902 diary, he wrote: "This journal is strictly private, and none should look upon its pages save with reverent eyes...." Much later, after the Rockefeller Foundation had made its financial contribution to the biography project, John D. Rockefeller, Jr. suggested to King that he owed it to the Foundation not to destroy the diaries. King firmly rejected this argument. (Diary, March 4, 1950)
Studying the question after King's death, the literary executors consulted Edouard Handy, who had been King's Private Secretary, from 1936 to 1950, and who had personally taken the dictation of most of the diary for these years. In Handy's opinion, King intended the parts relating to his public life to be available to researchers, but he would not want passages made public if they contained information given to him in confidence, or anything that might hurt the feelings of living persons or their descendants. Handy recommended that excerpts from the diary, relating to King's public life and political career, should be made for the biographers. It was agreed that McGregor would select extracts for the early years, in line with these considerations, and Handy would prepare extracts for the years when he was King's Private Secretary.
As work on the journals progressed, it was discovered that the diary for November 10 to December 31, 1945 was missing. Its whereabouts is still not known. It is the only volume of the entire diary, 1893 to 1950, that has not been accounted for.
Professor R. MacGregor Dawson of the University of Toronto was chosen to be the biographer. All of the King Papers, including the transcripts of the diary, were made available to him.
In 1955, it was discovered that an employee in the photographic section of the Archives had microfilmed parts of the diary and sold the microfilm copies. How much had been filmed and how many copies were made is still not known. But the fact that some of the diary was in circulation added to the argument that the original should be kept as proof of what King had actually written.
Dawson completed the first volume of the biography, which was published in 1958, but unfortunately he died in the same year, before the publication. Professor H. Blair Neatby was appointed to replace Dawson as the biographer. Neatby later married Jacqueline Côté, who had become the leading archivist of the King Papers. In 1960, J.W. Pickersgill published the first volume of his four-volume work, The Mackenzie King Record, based on the diary for the years 1939 to 1948. The question of whether the diary, or any parts of it, should be destroyed, remained unresolved, but opinion was moving toward preserving all of it. The existence of unauthorized copies was one consideration. Another was the question of academic integrity. In the words of archivist Jean Dryden, "...Once the diaries had been used by one historian, they could not then be destroyed without leaving the Executors open to justified accusations of distorting and crippling the history of the King era."
But perhaps the most important consideration was that, as work proceeded on the diary, the literary executors gained a deeper appreciation of how extraordinarily valuable this document was. For those who cared deeply about Canadian history and about Mackenzie King, the idea of destroying the diary became totally unacceptable.
However, there remained the question of who should have access to it. In December 1971, the literary executors decided to open the diaries to the end of 1931, to all researchers. The historical value of the document, and the passage of time, were factors in this decision. Historians and other researchers were delighted to have this material available. But soon the executors and the Archives staff were receiving many requests for access to the later diaries, from historians working on topics relating to the Depression and the Second World War. The handling of these requests was taking a lot of time. In October 1974, the executors authorized the Archives to open the diaries for 1932 to 1943. It was also agreed that for each subsequent year, the diary would be opened 30 years after the end of the year. So, for example, the diary of 1944 would be opened on January 1, 1975. The entire diary became open on January 1, 1981.