Welcome to CC and the world of modern photography.
This is a well worn discussion. Surprised at BT Police - you're sure it was genuine BT Police?
Jim and i have never actually seen them despite asking for their presence on numerous occasions

As for the Nuclear guys, it is a sad fact they have to go pointing guns at any one with a camera as Jonathan has mentioned on one or two occasions down at his local Nuclear Plant.
I'm sure I've got a picture or two of a flask if you want one for your collection - and I'll even include some men in white suits waving Geiger Counters around!
It is a sad fact of life that you must get familiar with being questioned over your activities. I tend to carry a multitude of ID with me now for this very reason - sadly.