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Try to get on with your neighbours for chrissakes
if you want to see what happens when you fall out over possible future damage to something that doesnt belong to you ( to wit the BT cable )
watch 'Nasty Nieghbours'
I find this compulsive viewing since my family spent £10 000 in 1994 on a neighbours dispute ( well he did say and then do .... " I am putting up scaffolidng on your prooperty to rebuildt and convert a barn and I wont pay for damage... )