Not an expert and so you might know this already - Bisley is still around, they make work clothes and are very popular for people on the land. Maybe you could find their contact details and email head office for some help with dating labels? Fletcher Jones is excellent quality, and usually pure wool in women's skirts in my experience. They are also still open so again, you may be able to contact them about dating pieces. There is still a lot of their stuff around, even their old pieces, as it was a hugely popular brand. Quite a bit online about them as David Fletcher Jones was very important in Australian fashion. Prue Acton is similar in that they made high quality, very popular pieces. To my understanding they often have good resale value. Other than that, while I recognise other labels I really don't know much about them sorry.
Do you know Tom McEvoy? He is researching Australian brands and designers. You could contact him through facebook: https://www.facebook.com/tommcephot...NI-gTqWhV3SoRic1VLQy4bv6nGsHiJ-iciriE&fref=nf
I've had most of these in my collection too, and research Australian labels. Most of your labels are Melbourne so perhaps that's where you're collecting? Here are some of my blog posts on labels you've included: Prue Acton. Len Vogue. Acorn Gowns. As Alice mentioned, Fletcher Jones were very big. Here's the 'About Us' page from their site. JC Williamson are an interesting one: a significant 19th century theatrical impresario who established a theatre company. So your label is likely from a theatrical costume. More here on Wikipedia.