St Agnes is a suburb of Adelaide, South Australia.

Facilities and amenities on the suburb include Ardtornish Primary School, founded in 1882, and the Steventon Post Office that opened around January 1859, to be renamed Tea Tree Gully in 1872, and Teatree Gully in 1925.

Tea Tree Gully changed again in 1966 and finally became St Agnes in 1969.

[3] The original school was built in 1842 on the Lower North East Road in Hope Valley, and named after Ardtornish Castle in Scotland.

[7] An extensive history can be found on the School's website[8] along with a slightly shorter version "for younger readers".