The two insulators on the lower right really intrigue me. From my many years of spotting CD 134 Pennycuick insulators from the ground (whether they turned out to be unembossed, CEL Co's, Pettingell Andrews or Diamond-Ps) and being correct most of the time in identifying them up in the air, I will bet those two unused pieces are Pennycuick-related judging by their unique "look" to them...