Thanks to all for your comments. Very much appreciated.
Chris, it was shot from the north side of Macedon near Hanging Rock. I don't know how well the very faint OIII areas would show from Melbourne. As it was, the OIII stack was quite noisy with a reasonably dark sky (SQL 21.3), whereas the Ha was very clean.
Not sure when I'm going to get the extra OIII - this dark time looks unprospective
, so it's probably a month away.....
Mark