Took a closer look at one of the old hook-ups. There's actually a 4th hook missing an insulator.
I've been told the 3 phases were prob. carried on heavier insulators than the neutral cable hence the 3 phase insulators survived intact. The neutral insulator's actually being used to attach the final clips for the modern cable.
It was 380V to bigger homes and terrices had a 3-phase hook up at the end of the block feeding each house 1 phase + tacked neutral along the facia.
