O conditus and O diosmifolius are said to be the most likely ones in this area, I haven't seen/had identified either of them. Whatever they are, there seem to be quite a few of them even though I've only just noticed them as being neither Cassinia nor Bursaria. My first guess was Kunzea ericoides.
I think its a tad large for O diosmifolius, but O conditus is a good suggestion. I'll have a look and let you know, we should be able to resolve this one.