That's one of the first questions we ask when we visit a customer.
In this case it was no existent. The plumber had replaced it with a boiler care system which was also feeding their drinking water. Yum yum.
So we took it off and replaced it with a stopcock. Relagged the pipes and then fitted a block salt water softener inside the house.
Its really important to be able to turn your water off in an emergency.