The cold tap has been difficult to turn on since I moved in I have looked to try to fix it myself, and have had the plumber in to look at it too, but it is, to coin a phrase, buggered! The only solution is to change the tap, which involves draining the system (as there are no mid-point stop-cocks fitted) and get under the bath to cut the pipe. If a matching tap can't be found, then both would have to be replaced. Add to that the grouting on some of the tiles looking like it needs repair, and it becomes a bigger job. the bath is an old style heavy ceramic ( I think ) bath