I have a question that I've been meaning to ask for a while now. When we visiting London in late June, we were in Paternoster Square taking photos of St. Paul's Cathedral and the statue of the shepherd and sheep. We were very quickly approached by a man who appeared to be a security guard who politely but firmly informed us that we were not allowed to take photos of any of the surrounding buildings. We explained that we were just taking pics of the statue and St. Paul's, and he said that would be no problem, but that we could not take photos of anything else in the square. We observed several other people with cameras being approached by this man as well. I'm not sure if it was just a general security thing (it was the day that the new Prime Minister took office), or if there's something very interesting going on in one of the offices. I visited in October 2006 and took photos of some of the buildings, and no one said a word.
I'm just really curious as to why he was so concerned about people taking pictures in that area.