The harassment of photographers, especially in the UK, is of course ridiculous. Terrorists don’t appear to make a big show of photographing sites before bombing them. Besides, in this day of tiny digital cameras that fit on everyone’s mobile phones, you can take photos of something with anyone knowing you are doing so.
From Bruce Schneier’s excellent blog, links to reference cards that explain your rights as a photographer in public for the USA, the UK and Australia. Apparently the English speaking world is affected most by what Schneier has termed the “War on Photography.”
UK Photographers Rights – UK. I would still be concerned about a statement from the Brown government, though.
Street Photographer’s Rights – Australia
and a commenter offered this for Germany – in German of course, but the Polizei would be able to read it.
Basically, you still shouldn’t take photographs of government installations like military bases of course, and power plants, you know just like the USSR or modern China. Wearing a turban while armed (with say a Canon EOS-1D) probably isn’t a good idea in London.