The list of War Office serial numbers shows blocks of numbers allocated to contracts with manufacturers.

C3923783 was issued to a BSA WC10 and C3927289 to a Bedford MW anti-tank portee ! In between, there were Humbers, Guys, Crossleys, Morrises - all sorts but no M21s !

If it were mine, and bearing in mind that it appears to have been transferred to The War Office in May 1940, I think that I would use a number from contract C7370 (first deliveries were 1/6/1940) which seemed to comprise various machines supplied by BSA from their factory stock - or maybe built from parts - there are no records but we know that it included 212 600cc machines (mainly ex-Dutch contract), 147 standard 500cc and 600cc and 167 350cc machines and it used the numbers C4191485 - C4191553, C4191584 - C4191627, C4191743 - C4191748, C4191761 - C4191801, C4191834 - C4191854, C4191866 and C4191959 - C4192302 !

No-one can say which numbers were allocated to which motorcycle, other than that C419216x(?) was a Dutch specification M21.

I've just had a look in Orchard & Madden's book and it lists engine number WM21 356 as being supplied under this contract, but no mention of the frame.

the enthusiastic person that i am already painted 1 number on the tank. The number i painted is 3927251. To not repaint my whole tank i think that changing 1 digit should be a BSA contract right? 3929251 At least i have seen pictures of BSA M with this range.

Thank you for all the help. appreciated.

Hi Prinsen

Your first number is for a Bedford 15cwt Anti Tank truck with a Z instead of a C in front of the number.

Your second number is for an BSA M20 from contract C5110 with a frame and engine number of at least WM20 5001.

I couldn't live with either of these knowing that.

The BSA factory ledgers are rather difficult to understand and this is quite typical of the odd system or amazing number of mistakes?

The WM20 frame book has

Frame Engine Tally Date
356 ...356 ...9257 .3/11/39 WM21 JWM Forsyth Cairo
2996 ..2996...10288.30/5/40 WM21 War Office London

The WM21 engine book has a double entry for engine WM21 356

Engine Frame Tally Date
356 ...356 ...9257 .3/11/39 JWM Forsyth Cairo
356 ...2996 ..10288 30/5/40 War Office London SW1
2996 blank

The WM20 engine book also has

Engine Frame Tally Date
356 ...2996 ..10288 30/5/40 War Office London SW1 (this entry is crossed out)
356 ...2987 ..10013 28/5/40 War Office London

Going back to the WM20 frame book which confirms this extra WM20

Frame Engine Tally Date

2987 ..356 ...10013 28/5/40 WM20 War Office London

In conclusion the frame and engine ledgers don't agree so there is definitely a mistake but I'm not sure if we are talking about one or two motorcycle being delivered with the same frame number? With BSA the engine number appears to have been more important and both WM20 and WM21 machines had a WM20 frame number.

But going back to what number to paint on your tank, why put one on at all, some machines had a number on the front number plate, others had a formation badge painted over the number.

Rob

email (option): robmiller11(a)yahoo.co.uk

Hi Danny,

Well, you should only have one number on your petrol tank! To be precise: on the nearside (LHS) of the tank, a white number in a black rectangle with white outline, not the white number on khaki background on both sides of the tank! This was only used much later...

Regards,
Jan

email (option): wd.register(at)gmail.com

Hi Jan,

Ive seen many pictures indeed with the rectangle. But also many with the white c39xxx numbers directly on the tank. That i put the number on the right side was indeed unknown to me till today