In your area did you ever use the electrical mains earth?
I was quite horrified when I was converted to a party line back around 1980 to find that the required earth connection was made to the earthing block adjacent to th electricity meter. (We had a concrete path all around the house, so no easy place for a spike.)
Used to get a bit of hum on the phone as a result.
When we were eventually back on a conventional line, only the push switches were removed from the phones, the earth connection remained.
<n>ildram Broadband2g0 MaxDSL
"Make something idiot-proof, and they will build a better idiot."