Thanks Muskrat and Sparx for your comments. I agree with Muskrat that the A's went to +ve earth, probably 1950 ish coinciding with the introduction of the A10 and shortstroke A7 (this is backed up by Haynes and Bacon - whilst they are capable of getting things wrong they do get most things right). Also, Sparx's comment, absolutely right, if the diagram just marked battery connections as such without reference to polarity that would be fine. However, there are other issues with the wiring diagram, the lighting switch connections are incorrect and the fuse unit supplied isn't shown on the diagram; that latter is only a minor point but customers who are a bit 'electro-averse' need as much help as they can get and any opportunity for confusion needs to be removed. It's much easier to give people a wiring diagram that is absolutely correct than trying to help customers rewire their bikes down the telephone! But my main point was 'When di the A's go to +ve earth?' as the Wassells Guru was absolutely adamant that this happened in 1956, contrary to popular belief. I am, of course, producing my own wiring diagrams to go with the looms. It's a pity about the diagrams because the looms are excellent.