This technique is frequently used by water companies. A private sewer
which
passes under my garden - altough it doesn't serve my property! - has been
lined in this way.

What a fantastic solution.

I haven't excavated the pipe fully, but I suspect it is totally smashed in
at least two places as I have uncovered some large chunks of pipe.

I may pursue the insurance option. I am starting to think that the problem
is one of those that get worse and worse the deeper you get into it.

Colin