[spanishfan]

The law let you photograph everything you can access while you're in public zone, even people, the only thing you must be careful is with under 18 children and of course if someone hide his face, not force him to let you photograph or make a persecution (is that the word? -_-).
Of course, one thing is the law and other thing is to be polite so if someone don't want a photo, don't take it. If I ever take a pic of someone and this person ask me to delete it I'd probably delete it.

Well, this is all I know about it, but of course I could be wrong or UK maybe have different law.