Robert Lay became Mackenzie King's chauffeur in 1932. Earlier he had been chauffeur at Government House for Governors General Lord Byng and Lord Willingdon.
Lay was an important member of King's personal staff, and the diary contains many references to him. He was one of the staff members King took with him on the train during the Royal Tour of 1939. King wrote: "Had a little talk with Lay....spoke of my appreciation of his work and loyalty." (Diary, April 28, 1939)
As well as driving for King, Lay helped out in a variety of tasks. For example: "Lay brought some rambler roses which his father-in-law sent for planting," (Diary, October 2, 1939) and "Lay looked after little Pat." (Diary, September 4, 1940) King arranged for Lay and his family to stay in a cottage at Kingsmere during the summer.
When the Prime Minister went to the San Francisco conference in 1945, Lay was one of the servants left in charge of Laurier House. (Diary, April 19, 1945)
In February 1950, Lay was appointed Chief of Stationery of the Senate.