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Thanks for all your suggestions, folks. just to answer your questions .... it's a two storey property converted into two flats, she's got the ground floor flat. We're under no illusions of the possible cost of installing a separate stopcock for the garden tap, but do feel that it needs it. It's pretty daft for the only way to turn it off is to turn off the water to the whole flat! We have got some tap insulation things, which we're fitting for her over the holidays, and she's got some of that polystyrene tubing stuff for the pipe, so hopefully that will do the trick in the meantime. And, yes, the outside tap is exclusively hers, no-one else uses it. Thanks so much for your help folks, much appreciated.