Interesting subject. I am always surprised to see that you can quite easily buy a digital SLR airside and nobody says that you cannot use it. There are no signs telling you in any gate room that you cannot use it. When stopped by a non airline aligned 'searcher' all they can say is "its policy". What policy? Its not covered in any lecture or briefing when you pick up your airside pass.
Its quite funny how many camera phones came out at LHR when the first A380 came in. The plods weren't interested that day................When ever there is a prang the phone camera's are out within seconds.