Thre's some really smelly oil called Renardine available from hardware stores and garden centres. It is said to deter foxes and other wildlife, instructions on can. When we moved here, our garden was also home to a fox, but we have a dog and when the dog moved in, the fox left. I was a little sorry but not very. Its not the danger factor, it's that their poo really stinks and if you tread on it in the garden or the dog rolls in it, as ours did when we visited for a second look at the house before buying (house was empty)...what a nightmare day that was, anyway as I was saying, it stinks and is very clinging, major deoderising prob.