Prewar military bikes had numbers without the prefix in line with civil bikes. Initially, spare frames and engines were numbered in line with the ordered M/C's. The number of frames (and sometimes engines) found without the W may however be an indication that the correct numbering of spare/replacement frames might not have been so rigorously followed.
Dating the bikes based on the contract numbers is a tricky issue.Bikes made on a contract date in one year could very well have been delivered the next year.Also found on many early engines is a Quality control stamp consisting of a broad arrow over an M and with a number underneath.On all engines, bore and stroke are given at the right hand upper corner.This wil inevitably be an incomplete inventory (many bikes lost, not everybody responding etc) , but it will hopefully give some insight in the numbers.
The W numbers are the original WD16H War Department numbers from late October 1939 onwards.
Gearboxes also have an identifying serial number, but they can not be used for dating a bike.
If you want to help unravel the past, please send me your frame and engine numbers (and preferably the others as well).
Originally, a bobbin of red thread was taken to Rachel's tomb and wrapped around it seven times.
Then small lengths of that thread were worn on the left wrist, not simply to ward off the evil eye but to remind the wearer that he or she can be more mindful of his or her own behavior and intentions.
Headstock frame casting numbers are found at the left, aft side on the steering head, saddle casting number is found on the left-hand side below the saddle.