I think it's safer to say that if photography by the actors has been a precursor to attacks real or planned, it wouldn't be a secret. Other than the Mumbia hotel attack, no evidence of this has ever surfaced.

Like you, the authorities simply imagine it to have been the case because it seems a reasonable assumption. Others assume that the reconnaissance (if any) would have taken other, less ostentatious forms.

Depends entirely on what theoretical position you want to take. If you steadfastly believe that unusual=suspicious and photography=terrorism no amount of discussion, rational or otherwise, is going to have the slightest effect.

You may well be right. Here you go: http://photolibrary.baa.com/Glasgow-...search=glasgow .