Thanks Mike, I'm still trying to make up my mind as to the level of threat this plant poses as an invasive weed. It seems to only occur in fairly heavily disturbed places but your photo suggests pretty intact habitat.
I have adjusted the location because it was actually under the trees, next to the Berberis. There didn't seem to be any bare ground. I have seen isolated plants on the north side of Mugga Mugga but the big infestation is south of the quarry, spreading into the reserve. There are also garden plantings in Isaacs.
I have now found one in Callum Brae. There is a patch at the top of Hindmarsh Drive in the cutting at the edge of the road so it could be on Red Hill too.