Thanks for your answers :) . Seems putting in a new stop cock would be the best way of sorting out my supply from below (or rather, interrupting downstairs). However, if I turn of the water in my flat I think it would turn off upstairs as well! Not sure, though.
I own the middle flat of three in a converted terrace house. The three flats have a shared water supply from the mains, and the (only) internal stopcock in the downstairs flat cuts off the water to all 3 flats.
I need to do some refurbishment soon, and I am worried about having to cut the...