Hi Lauren, I speak as a retired police officer, and I have to admit I am very embarrassed by the actions of some of my colleagues these days, who seem to lack even the most basic common sense required for the job. But do not worry, follow these basic rules if you fall foul of an idiot PC or PSO: Never loose your temper, be polite but firm and ask for the reason you have been stopped. Make notes if possible there and then or as soon as possible after - if they object - you tell them that you think they are behaving unlawfully and you will be making a formal complaint to the IPCC and suing them for false arrest/detention as soon as they have finished because they are acting in a manner contrary to the ACPO guidelines on Police and Photographers in public places. Make sure you see the officers warrant cards and record their collar numbers. If in plain clothes they must show you a warrant card. If there are people passing by try and ask one of them to be a witness to what is happening but never raise your voice, never get agitated or get excited - this will only give them an excuse to switch to disorderly behaviour or something else. If they want your name and address, they have no right to demand it but I would give it anyway, saying you do so under protest. They cannot seize your camera or delete photographs without a court order or warrant. However if you are in front of Thames House where MI5 hang out, expect to be shot on sight or scragged by the SAS - your relatives will be told they thought you were called De Menez or Bin Laden
Joking aside, suing the Police after such an event is the only thing that will stop this stupid behaviour on their part - it will also enable you to buy some excellent photographic gear if you are a) unlucky enough to have it happen and b) if you persevere afterwards.