In some ways I feel more safe that you can't carry mace or a stun gun.... Not only "good" people can buy stuff like that, and there's just too much room for error or misuse.... But that's just me. When I'm in London ('bout once a week) AND when I'm at home (the 'burbs aren't always that safe at night either...) I just use basic self-defence stuff I've learned in classes in the past - carry my keys in my fist with keys sticking through the fingers, being super alert, never talking on the phone, handbag not dangling, knowing where I'm going and looking like it, etc., etc. I came of age in San Francisco where the neighbourhood can turn on you over the course of a single block, so I think I carry myself pretty well. But I also never take for granted that I'll be OK....