Unlike other museums, the Australian War Memorial has chosen to make the original vehicle registration books accessible to the public.  All original books have been scanned page by page and put into large PDF files for everybody to search.
As expected the books show all the Nortons which have been officially registered by the Australian Army.
The books also gives some history for each vehicle.
It is also clear that the books do not contain  the motorcycles used by the Australian army in the Western Desert and will therefore not give all answers.
It will also not give information on MC's used by RANavy and RAAF.

To ease the search for a specific engine number I have categorised them all in one excel file.
If you want a quick answer, drop me a line and I can tell what C number(s) fits to your particular motorcycle if in the list.
 wd16h@telfort.nl
  
It appears that a single motorcycle can have had up to 4 different C numbers over its life.
With the census numbers it is much easier to go through the various books.

(I initially wanted to add the Excel to the website but experience has shown that my elbow gease is re-published on other websites without even a reference/credit to where it came from).

All the books themselfs can be viewed and downloaded via the links given here. I only added the ones which refer to Nortons.