Well it all depends on how much effort big brother is willing to devote to the exercise. PAYG phones are relatively anonymous, but the network can track exactly where the phone has been, and so it wouldn't be all that hard to track it down. Blocking it would be even simpler.
I suspect that if any images of relevance to the goings-on in Ipswich were found, big brother would devote the necessary effort in a heartbeat. But for a few pics of some military toys? I doubt it.
It seems pretty obvious to me that there needs to be a control policy for image recording in an environment where protectively marked material is commonplace. The James Bond types of 30 years ago would have given their right arms for a device smaller than a cigarette packet that could surreptitiously take photos of a new shiny thing and send it anywhere in the world in a few seconds. However, said device could also be used to take commemorative photos of the Sgt's Mess Christmas bash, and what's wrong with that? A balance needed, methinks.