On Sat, 29 Sep 2018 17:03:41 +0100, "Brian Gaff"
wrote:

Ahem, there are always live and neutral in all my ceiling roses even if the
switch is off, and to me this disproves your hypothesis completely

Depends on your interpretation of my hypothesis. When I said the
action takes place on the red, I did not mean no return path was
needed. I do have some clue about electricity. I meant the
'diversion' and switching takes place on the red.