Tony in the Tarn

Thank you for these replies. OK, I will go very carefully then. I presume that the marker is generally vertically above the pipe?

I live at the end of a long track and we are the only house. Part of the track is over a gully and over the years the gully has started to undermine a wall on the downslope. So I need to add a culvert. No problem; my father is an engineer, suggested a method so all fine. Only question is, 2 feet down I dug into a cable. It is tiny (so 1mm), metal line, covered with black insulation and then wrapped in a modern looking luminous blue plastic webbing that has badly deteriorated. Given the age of the road (so gravel over an older metalled road surface that appeared to be intact) I was surprised to find anything, especially something new looking. Point is, nothing happened. Internet/ phone fine, electrics fine. But I'd still like to know what it is. Any ideas? Old telephone wire? A bomb?