Ok i got the feedback i was after, from a very knowledgable guy "Shippingsteel" on the Great War forum,..."That's a nice looking bayonet you have there ... and a very interesting example to boot. There always has to be an exception that pops up to confuse things, and this is one of those.! It would have been sent out in a batch of late 1911, early 1912 Enfield production bayonets that were shipped to New South Wales. I have others similar dated recorded in my database.These other examples are all marked with the 2MD serial numbers which began to be applied in the years shortly before the war. For some reason this one does seem to have missed out. The D^D marking is usually recognised as an interwar period marking so it is extremely unusual to be seeing this marking on a hookie. But there you go, it must have surfaced again later on."
I hope it ok to quote him from another forum..hes very knowledgeable on these
Australian Bayonets - Arms - Great War Forum