Bob,
Got it, but in my defense (and lord knows I often need defense, because I can be an idiot), you said this: "I believe that the later A7 and the A10 from 1960 onwards had both an alternator and dynamo fitted they were controlled by the headlight switch", which does, indeed, imply that both were fitted, so I inferred that's what you meant. Sorry for the misunderstanding. I now understand that that is not what you meant. In any case, ride happy.
Richard L.