Thanks for the prompt @natureguy. The NSW BioNet Atlas records centred on this property show S. monticola and S. sericea. Zooming in the plant the blunt leaf tips and lack of hairiness of S. sericea suggest S. monticola. I've also compared it with a flowering S. monticola sighting pics which I am confident about (but haven't yet uploaded) and the habit and stem characteristics are v. similar. So I'm now calling it as S. monticola.