Production numbers and dates

The first direct source to find the information would have been the Norton Assembly Books or Engine books. The missing Norton Assembly Books for parts of 1939 and 1940 and entirely for 1941 up to August 1945 make it impossible to be specific on the production date of the majority of the motorcycles produced during the years of the actual conflict they were made for.
The reason for the missing books can only be guessed. The books themselves are heavy linen bound thick covered ledgers approximately 40 x 40 cm and 5 cm thick.They weigh a considerable amount and take a lot of volume. This may have led at one time to the decision to clear out the books that were not of much use. Many bikes no longer existed and there was no interest in military bikes (then!). Its also not clear if it happened in between the mergers with AMC and Villiers or even after the demise of Norton Villiers when the Assembly Books were turned over to the Metropolitan Police, Stolen Vehicle Squad. From the Police they were First offered to the single marque clubs but this was overridden and they went to the Science Museum which initially made the books available to individuals. After it was found that irresponsible, egocentric visitors tore (parts of) pages out of them, they put them behind bars so to say. A policy change at he museum then resulted in the books being offered to the VMCC as the museum did not find it "their task"anymore to be a guardian of the technical history on motorcycles. It is perhaps fortunate that the ledgers are now available for examination at the VMCC as some of the one-make clubs are extremely possessive and in many cases unhelpfull in an attempt to "prevent the construction of "original" bikes" by people wanting to make money.

All other sources for information are  indirect. They describe what should have been or what was, but only for parts of the production. British army purchases went through the Director of Army Contracts initially, later the Ministry of Supply. The orders for the Navy and RAF were arranged by the individual services. No records have surfaced from either of these two services. The RAF museum has stated that there are no surviving records on Motor Transports. Other museums do not react to requests, I have not tried the Navy but fear the same treatment. It seems only part of the DofAC/MOS records have survived in the form of Contract ledgers (WO294 books) at the National Archive (formerly PRO) in Kew, London and some records at the former Museum of Army Transport Beverley which may now be with the Royal Logistics Corps Museum. Another DofAC/MOS survivor is a card system which seems to have its origin at Chilwell. Some of these cards are kept at The Tank Museum at Bovington. For ease of reference I call them "demand/contract cards" as they seem to describe the quantity of bikes demanded and subsequently show the ticking-off of various quantities received on a certain date. Unfortunately, these cards are also incomplete, and the information does not always tally completely with expectation.
A book like "British Forces Motorcycles" (BFM) from Orchard & Madden also has to be regarded as an indirect source. O&M also mention the difficulty in providing the correct information as a result of the many "corrections" and alterations to official documents and sometimes contradictory information. Even when  being able to study the originals there remains an element of uncertain information.

I am in the process of compiling a list showing all the information available including the sources used. Its a hell of a job and will probably never be finished. The intention is to make it as complete as possible but to keep it manageable I will have to edit many details from the website version. Analysis of the assembly books also make it clear that there is one consistent mistake in the official contract ledgers which is repeated in the "demand/contracts cards" as well. Contract C7353 was supposedly made at a rate of 2000 bikes a week. It is however clear that the maximum weekly output from the Norton factory was around 500 machines. It looks like the authorities made a "typo" and probably meant to refer to 2000 bikes a month. Looking at the overall 16H production it is found that a number of contracts seems to have been made parallel, making dating of bikes even more confusing.