Percy Simpson as the Old Boys Union (OBU) in August 1906. This was some 21 years following the establishment of the school in July 1885, making it one of the oldest continually-active alumni organizations in Sydney. The history of the association is strongly tied to the development of the school from being 'The Choir School', educating mainly choristers to an Intermediate level (equivalent to the
School Certificate), through to the co-educational institution it is today. Prior to the school offering the Leaving Certificate for the first time in 1960, the activities of the OBU were significantly curtailed by the fact that many students matriculated at other schools. The OBU became the OAA following the introduction of girls to the school in 1999. In addition to fostering connections between the former students, the OAA also aims to maintain a tangible link between this community and the wider School community. The activities of the OAA are strongly linked with the activities of the school and other associations including the Parents and Friends. The association also supports the school through financial contributions and, as a result of recent growth, the establishment of the OAA Scholarship for the child of an Old Andrean. These contributions are made possible through financial membership and direct contributions from members.
