conductor rails at trap points

I've been doing some research into this for my 70's era model railway, and am now a bit confused. As a kid at the time ISTR that some trap points at the outlet to sidings and bay platforms were electrified into the sand drag, which seemed a bit silly to me at the time. I have been trawling for photographic evidence of whether they actually were or whether my memory is now fuddled. The outlet from White City depot appeared to be electrified from a video I have, whereas other places seem not to have been. Presumably if it was done it was for the sake of completeness, like having ramps at the end of sidings even though no shoes could actually venture that far. Can anyone help clarify? Many thanks. Pointers to any photos greatly appreciated.