Hi John

Its in the DME circulars under the medium "When Necessary" section

B.390 20/1/43 Horn - Revised design & location. B.S.A. M/C.

Presumably alterations to existing machines would have happened at roughly the same time as changes in the factory.

Rob

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

Its one of very few which I have seen copies off, wish I could find more. And interestingly it seems to show a drawing of a WB30.

Rob

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

Thanks rob
It seems then that up to 1942 the horn was under the seat

Yes it looks like a wb30 engine plate but the horn bracket shown in the illustration appears to be a different type too to that of an m20

Br
Jo’b

email (option): jonnyob1@googlemail.com