I must say, in all my time here, I have never seen a connector like the one you've posted in your 3rd picture, were these actually made for that purpose?
To me that looks an awful lot like a 3-way trailing socket, i.e. supposed to be part of an extension lead. It could also be a plug-in 3-way adaptor with the prongs cut off.
Anyway, was that contraption backfed by stuffing wires into the holes on the left?!?
