| Name | Year | Details |
| Nigel Oakely | 1986 | |
| Richard Oates | 1989 | Semi-finalist |
| Clare Ockwell | 1997 | Finalist |
| John O'Donnell | 1995 | Semi-finalist |
| Arnold O'Hara | 1975 | |
| Margaret-Louise O'Keefe | 1986 | |
| John Old | 1979 | Semi-finalist |
| Derek Oliver | 1985 | Semi-finalist |
| Philip Oliver | 1974 | |
| Barbara O'Meara | 1989 | |
| 1995 | ||
| George O'Neill | 2004 | |
| Robert Orr | 1976 | |
| Stephen Ortiger | 1984 | |
| Archie Orton | 1973 | Semi-finalist |
| Isabel Osmont | 1990 | Semi-finalist |
| Malcolm Ostermeyer | 1974 | |
| Michael O'Sullivan | 1987 | |
| J Oswald | 1972 | |
| Paul Overall | 1993 | Semi-finalist |
| Frances Owen | 2000 | Semi-finalist |
| Patricia Owen | 1973 | Champion |
| Peter Owen | 1979 | Semi-finalist |
| Jeremy Owenson | 2003 |