Does anyone know if BSA offered locking petrol caps as an optional extra? The 4-1/4 tank that came with my A10 plunger bike has a brass collar let into the opeing of the tank. A standard cap fits onto this but there are three channels on the inside of the collar that I assume to be for the locking mechanism of a locking cap(?). I've bought another used 4-1/4 gallon tank but this has the usual folded-over steel opeing to which the cap attaches with no internal fixings. As I haven't seen a tank fitted with such a collar before I thought I'd ask. It was an export bike, if that makes any difference.
