There were 100s of Microtis in this area; close to 20 in this patch of approx. 2square meters. The first photo shows part of the patch including a specimen with a flower spike close to 900mm tall. The second photo shows details of a smaller specimen taken at the same site a couple of days earlier.
The updated ACT Census of vascular plants Version 4.0, 2017 does not list Microtis unifolia. The species listed in the Census under the common name "Common Onion Orchid" is listed as Microtis arenaria. Orchids are confusing...
Given the size of this plant it likely to be M. unifolia. However, from discussions I have had with Mark Clements, the name may have changed to M. arenaria.