Hi there, I have a bit of a mystery...

we've just tried to turn off our water from the stop cock near our
property boundary. Lifted the lid, the hole was full of mud (as you
would expect) but we excavated, found the tap, turned it clockwise
until it reached the end... and absolutely NO effect on water pressure
in our house (or next door who share our mains from the street). We
even tried turning fully the other way, and still no effect.

There are no other visible signs of a stop cock outside. The around
the house back and front is old concrete and the stop cock we tried
had been carefully concreted around so we assumed that was the one.

We can turn off our water at the inside stop cock obviously, but there
might be a reason to need to turn off further back. I'm completely
puzzled by this... any suggestions anyone?