Collection consists of material relating to William Lyon Mackenzie King from the estates of his brother Dougall Macdougall “Max” King and of his nephew (Dougall’s son) Arthur Macdougall King. Its major component is correspondence from Mackenzie King to Arthur King and also to Arthur’s wife Kathleen, over a period of twenty-seven years from 1923 to 1950.The first letter is dated 1923, a scant three years after the death of Max King, when Arthur and his twin brother Lyon were 10 years old and the last in the series is dated July 5, 1950. The collection also contains documents and ephemera relating to King’s death, funeral and will, received by Arthur King as a participant in those events; also present are issues of major Ontario newspapers that covered Mackenzie King's death and funeral as events unfolded day-by-day. A small selection of photographs, some formal and some snapshots, are also present. A selection of books retained by the family, among them works written and presented by John King and Dougall Macdougall King, also works owned by Mackenzie King as a boy, present a tangible reminder of the intellectual legacy of the King family.