| Julian Errington Ridsdale | 1964 | October 1964 |
| Bruce Millan | October 1964 | April 1966 |
| Merlyn Rees | 1966 | 1968 |
| John Anthony Kershaw | June 1973 | January 1974 |
| Brynmor Thomas John | March 1974 | April 1976 |
| Alfred James Wellbeloved | April 1976 | May 1979 |
| Geoffrey Edwin Pattie | May 1979 | 29 May 1981 |