I pinched it off another forum.
Ron
http://www.britishpathe.com/video/factory-making-bikes-and-mini-bikes/query/airborne+motorbike
email (option): ronpier@talk21.com
Very nice 
email (option): ahum@quicknet.nl
Quite right Bill. Can you think of a worse way to go to war? Ron
email (option): ronpier@talk21.com
I should think if you were heading for the trenches how you got there must have felt pretty insignificant...
.....Ian
email (option): ian@wright52.plus.com
Much care was taken as she throw the wheel onto the the pile 
email (option): horror@blueyonder.co.uk
Gosh Ron! You know that I've been studying these acceptance markings for a couple of years. Well, we've finally found one of the inspectors at work! At 1' 55" we see inspector ^M419 stamping a frame, after having done a brief inspection of the bike:
Welbikes were only produced in 1943, and for as far as I can see, they have all been checked by ^M419. But the same inspector was checking BSAs in 1944:
And Albion - Kitson Pease gearboxes in 1945:
Cheers,
Jan 
email (option): wd.register@gmail.com
It is strange that they stamped the Welbikes on a most flimsy easy to distort part of the bike. I watched him hit the frame but didn't cotton on that he was the inspector. Isn't it nice to put a face to a number
I think I might hang his picture in my shed. Ron
email (option): ronpier@talk21.com
Do you think this implies that the inspector always inspected complete motorcycles and that on the conventional bikes, the most convenient place to stamp was the crankcase but for some reason on the Villiers engine they didn't do that ?
I don't know... Obviously the Kitson Pease gearboxes were inspected without being fitted to a motorcycle. But the engines...? I have often wondered if this could also have been an inspector:
There's a hammer on the workbench, and engines all over the place. Could this also be an inspector, checking and stamping these engines...?
Jan
email (option): wd.register@gmail.com
He may have stamped mine.
Rob
email (option): robmiller11@yahoo.co.uk
Yes mine is 419 also. See how lightly they are stamped on such a thin tube.
Ron
email (option): ronpier@talk21.com
Same stamp on my Welbike
and the picture of my engine markings on the M20 have already been posted I believe 
A 1942 engine though.
email (option): martynhillyard@msn.com
What a shame some pesky German has shot a round through your frame number Martyn.
I now have a picture hanging in my shed of the very man who stamped my Welbike over 70 years ago.
Ron
email (option): ronpier@talk21.com
I know, couldnt tell at first when it had paint on. Just been worn down, only one number missing but a shame i'll never know. Ive seen another welbike worn down there so must be a common wear point?
Anyway Im surprised that much of the headstock was salvagable from the mods.
email (option): martynhillyard@msn.com
While we're talking about these acceptance markings... As I said, I am keeping a list with frame numbers and acceptance markings, as I'm sure that when I have enough numbers, a pattern will emerge, and this may reveal some more important information.
For the Royal Enfields I have a very complete list. Also for Norton I do have quite a lot of numbers (but more information is always welcome). But for the BSAs my list is still very small...
If you're the owner of a BSA with an acceptance marking, and your engine number is not in my list, please give me a sign. It would be nice if your numbers could also be added to this database! You can either add some pictures to this thread, or send me an email with the pictures.
Cheers!
Jan
email (option): wd.register@gmail.com