Ed,
This topic has come up before and the London Douglas Motor Cycle Club (LDMCC) was contacted to see if they would be interested in posting a copy of the spares list on the Douglas Motorcycle Forum (DMF). The response from the committee at the time was that the spares lists were supplied to LDMCC members only, since only members could buy spares. Presumably publicly posting the list would solicit a lot of queries for spares from non-members that would have to be declined.
It is important to note that the LDMCC and the DMF are two entirely different entities that happen to have a shared common interest in Douglas motorcycles. So if you want a list of the spares produced by the LDMCC, you will need to contact the directly.
As I recall, there only was a listing for the prewar spares, and that is likely out of date by now. The last one I saw was dated 2003. I do not believe there ever was a listing made of items carried for the postwar models.
-Doug