andytug
Switching the neutral wire was thought safer a long while back when switches were made of brass and ebonite and there was no earth connection in the lighting circuits. The high voltage was kept out of harms way near the ceiling. Older properties can conceal a multitude of traps for the unwary electrician or DIYer.
Even further back, electrical wiring consisted of two bare copper conductors stapled to the wall and covered with a wooden lath. I am led to believe my grandfather wired up several hundred new build houses in the Leyton area of London using this method as late as the 1920s.