Lectrician, when you said this was a common setup for farms in the 60s, it has just jogged my memory. I think I remember been told that the poles were installed in about 1952 but stood there for over 10 years with no wires on as the house did not have electricity installed in it until about 1963, the wires put on them when the house had electric lighting etc - I had also been told that at one point a lodger my grandmother had staying there tried to run an electric cooker from the lighting circuit!.
Also as I was saying above I know for sure that the house installation has never been connected to the earth on the armoured cable, I cant actually remember if it was connected before when we had three single core cables coming in the house so it may be as you say the earth on the pole is no longer reliable and perhaps this may have been confirmed when the armoured cable was installed.
Also as I was saying above I know for sure that the house installation has never been connected to the earth on the armoured cable, I cant actually remember if it was connected before when we had three single core cables coming in the house so it may be as you say the earth on the pole is no longer reliable and perhaps this may have been confirmed when the armoured cable was installed.