I have loads of foxes in my London garden and the only problem I've had is them once digging in a border. Oh and pooing a couple of times (but let's face it we've all gotta go somewhere and it's hardly nuclear waste!). Some people moan about them ripping rubbish bags - well, hello, get a dustbin. They are definitely not a risk to cats. One of my cats is a complete wuss, afraid of his own shadow, yet I've seen him chase a fox away.