Most of this has come from old Sydney Morning Herald articles, government files and ads, and Australian Glass only has sketchy information on the company. I'd originally thought that production stopped during the war, but there are definitely ads which come from after the war - but whether they were just cutting imported blanks again, I personally don't know.
Going back into the files, there are so many complaints about quality, some of which are quite amusing. They had a contract from 1934 onwards with the Australian War Memorial to make cut glass ink bottles for souvenir desk sets, the bases of which were made from the salvaged deck of the (first) HMAS Sydney, which had sunk. Of the first 94 bottles they made, 12 were rejected as having "blemishes in the glass, rounded instead of sharply cut edges, badly shaped insides, or very small openings," (according to J.L Trelour, Manager, Australian War Memorial, dec 1934). Another 16 were held back as having the same defects, but not as noticeably. In addition they were all different sizes so that the teak had to be cut to match each bottle. All of which is interesting (to me) but doesn't really help with your decanter, does it?
If you can wait a week or so I'll see what else I can find.