Slightly different situation but when I was near RAF Marham a couple of years back I thought I'd take a look at my old station. I wanted to take a photo of Marham's "gate guardian" Victor K2 (actually it's on the old parade square) so I walked as far as the barrier, but realised that I needed to be a few yards inside to get a decent shot. I asked the guard if I could go in just a bit further to take my photo. He agreed and I said "Dont worry, I'm not going to try and get further onto the base" He replied, "I'm not worried, if you try that I'll shoot you".
I think he was joking!