There has been a steadily increasing number of reports of police and security guards stopping photographers going about their perfectly lawful activities. In some cases, cameras have had to be handed over or memory-cards erased.
The average member of the public, according to several surveys, seems completely ignorant of the rights of photographers. Most believe that a photographer has no right to take a photo of an individual.
In fact, a photographer has the right to take a picture of anyone in public. Even children. As long as the photographer is in a public place, it does not much matter where the subject is even is this is their back garden. The copyright on any photograph is automatically with the photographer (unless they asign the rights to another party) – without a model release form though, the photos cannot be used commercially but they can be published widely (websites, magazines, newspapers, etc).
A few links: