electrical theory
I also seem to remember the change from +ve to -ve earth was said to be due to reduced anodic (cathodic?) corrosion effect on the bodywork with winter road salts thrown into the equation.
I have a vague memory of the engine starter aerosol being called something like Bradex. Found myself once or twice after spraying a dose into the air cleaner intake wondering whether to go and give it a 'start ya bastard' with the key or just stay there sniffing for a minute longer.