Tim Lamb ) gurgled happily, sounding much like they
were saying :

BUT: We couldn't turn the Water Co's plastic valve back on again.
It appears that the bit you turn has a rachet-like device that makes
turning it back on very difficult.

Umm.. I doubt the ratchet bit. My only experience of plastic meter/shut
off assemblies are those used by Three Valleys Water Co. in
Hertfordshire.
These have a removable T shaped plastic operator which fits into a
square socket on the valve.

The torque required to open and close the valve is significant. For
security reasons, I removed one from a field supply and subsequently
lost it! A replacement was supplied by the meter reader.

I'm also in Three Valleys, and had a new main stopcock about seven or eight
years ago - the previous one was seized solid...

There's a simple plastic lever to turn it on or off, and it requires very
little torque indeed.

There's no meter on my place, but there is a connector for one - If we were
to move to a meter, I gather they just fit a meter head to the existing
stopcock.