"Clare" wrote in message
...
On 18 July, 16:27, "JoeJoe" wrote:
Unless I am mistaken, those tap operate like a 90 degrees toggle - i.e.
assuming water in on. Choose a direction (say clockwise), turn 90 degrees
and water is off. Turn 90 degrees again, and water is on again, etc.

Thanks Joe, your idea sounded promising so have given it a go, but I'm
afraid still no change.

Not in my experience for water (although it would be for gas). My guess is
that the rubber washer has long since disappeared. A plumber might be able
to freeze it and then just replace the "removable" part.