ng 1921-1926 12. Arthur Meighen 1926 13. W.L Mackenzie King 1926-1930 14. Richard B.Bennett 1930-1935 IS. W.I.Mackenzie King 1935-1948 16. Louis St. Laurent 1948-1957 17. John G.Diefenbaker 1957.1963 18. Lester B.Pearson 1963.1968 19. Pierre Elliott Trudeau 1968.1979 20. Joseph Clark 1979.1980