>The real fix is to check all connections and make them fail safe. This means the male part of the bullet connector is on the earth side and the female part, the bit with the insulation round it, is on the 12V side.
>>it is impossible to do as he suggests without changing every terminal, because they're all male metal bullets on wires, pushed into insulated female connectors.<<
Indeed they are, but he was making the point that the female all-insulated half should be the one at 12V potential not the other way around.
Not impossible at all, and eminently sensible. The old glass cartridge Lucas fuses, usually 25A or 35A, were notoriously inaccurate in their rated protection, and would likely only blow at well over the rated current. Cheap fuses never were to be relied on for precise discrimination.