"Nick Brooks" wrote in message
...
In my situation where the water company stopcock is in the road and the
supply then passes under all the gardens in the terrace to individual
internal stopcocks, is it true that what happens after the stopcock in
the road is also not their concern?


The mains water is their concern. All of it. That is why they inspect
before connecting and backfilling.

I'd be grateful if others could reply as the above is of no value
whatsoever

Making the changes you are requesting counts as a new install and thus they
do have the right to fully inspect the water by-laws are obeyed throughout
the house. It really depends on your water company. Are you in Scotland ?
I've heard stories about them being especially pernickity.