Parallel connection near Rumbling Bridge

Electricity supply has been an endless source of fascination when I've been out. I noticed this above The Hermitage at Dunkeld. The main line has 3 wires but the spur off up the hill has only two. They come from the middle and the furthest edge. So is the middle the common neutral of a.c. supply? If so, why are there two lives? It reminded me of a household ring main circuit where live and neutral spurs go to plug sockets from a central ring. They are wired in parallel to each other, as is this.More research to be done.