Some current people will surely respond but allow me to relate a little tale from long, long ago. I showed a few controllers from Chicago round Heathrow Approach and we were looking at the radar. One of the guys, pointing to the range rings said something like: "Now let's see - that must be 50, 100, 150.. miles?" I said "No, 10, 20, 30 miles". All of a sudden they realised what a very tiny little place the UK is compared to "back home".