Previous OMA Chairpersons.
| 1957 - 1960 | Mike Pleming/Pat Dove |
| 1960 - 1965 | John Stainsby |
| 1965 - 1967 | Page Clowser |
| 1968 | Martin Coates |
| 1969 - 1970 | Mukhlis Oweis |
| 1972 - 1990 | Ian Henderson-Begg |
| 1990 - 1995 | Clifford Wallington |
| 1995 - 1998 | Peter Yarker |
| 1998 - 2000 | Robert Hill |
| 2000 | Rachel Golby |
| 2001 | Robert Hill |
| 2002 - 2004 | Michael Catterick |
| 2005 - 2008 | Ian DuPont |
| 2009 - 2011 | Geraldine Ellison |
| 2012 | Robert Hill |
| 2015 - 2017 | John Wallington |
| 2018 - 2021 | Ian DuPont |
