This idea came to me: What if I checked through AH.Com timelines, and made a list of presidents/PMs on it? If it is still being worked on, right next to it's name I will write WIP next to the TL's name.
37. Lyndon B. Johnson (Democratic), 1963-1969
38. Hubert H. Humphrey (Democratic), 1969-1973 (died)
39. Henry Howell (Democratic), 1973-1977 40. Roger MacBride (Republican), 1977-1981 (resigned)
41. Roy Cohn (Republican), 1981-1989 42. W. Fox McKeithen (Democratic), 1989-
UK
66. Alec Douglas Home (Conservative), 1963-1967
67. Iain MacLeod (Conservative), 1967-1971 68. Peter Shore (Labour), 1971-1981 69. Alan Clark (Conservative), 1981-
Canada
15. Pierre Trudeau (Liberal), 1968-1979 16. Alan Eagleson (Progressive Conservative), 1979-1992 17. Erik Nielsen (Progressive Conservative), 1992-1994 18. Paul Hellyer (Social Credit), 1994-