As an owner of a British car, I know a lot about the LUCAS syndrome. This electrical system was apparently conceived by a British prince called ''Prince of darkness''.
Those Brits had it all wrong. First, the electrical polarity is reversed (up to 1970) whereby ground is on the positive side of the battery and power is on the negative side of the battery. (this is not a joke). It mean the whole car is full of positive electrons all trying to return home (the battery) through negative wires going back to the positive side of the battery....
One day in 1970, the Brits realized they had made a mistake and decided to turn everything around.
The wiring system was designed (back in 1906) with the intent of having all of those nice electrons traveling in one direction (from minus to positive). When they reversed polarity, the wires were all fooled. (LUCAS only manufactured one-way wires.) To try to correct the problem, they tried selling SACUL batteries, but it did not work. They are still working on the solution.
JackD