Ive read various discussions on this subject in a couple of photo forums. In UK, it seems its pretty safe taking pics if people are in a 'public' place. Obviously, its a little more delicate when it comes to children, especially in the light of current sensitivities, so I steer clear of these situations. Sad really as when out and about you can't help but see the potential for a lovely shot. Like Annette, generally, if a person is featured in a shot of mine, they are usually silhouetted or at distance; but I do have shots of say, street performers in Dublin and couples along the beach. It just depends on the circumstances. I admit, I too can feel quite uncomfortable when out in public with my camera, and its a feeling common to a lot of photographers Ive met, both male and female. These subject discussions can open up all sorts of grey area situations. I too would like more info on the the legal stipulations regarding these responsibilities.
EDIT: Thought I'd do a search on 'The Law and Photography (in UK)' in google and found this:
http://www.sirimo.co.uk/ukpr.php Ive not read through it yet, but glimpsed some of the info. You may find something towards helping you with your question Rob.