A picture of the extra, external service outlet! Cunningly arranged so that it is fused by the pin main inlet fuse, but not switched by the pin on / off switch. I'd guess it was used to feed an adjacent pin? Generally the internal service outlet on a pin is fed directly from the line in before the fuse - this makes some sense as you can then work on the pin using the service outlet with the pin turned off or with line filter / varistor problems (by removing the pin main fuse).
and Mitch, I thought I'd start mine before you came along and showed how it should be done
