I remember visiting Davis Monthan in the early '80s, doing an article for Pilot Magazine, and the tour bus I ended up aboard was entirely coincidentally filled with a couple dozen Brit reggie-spotters who'd apparently come over on some sort of enthusiast tour. You can't imagine the bedlam as all of them peered through their binocs and called out numbers in hysterical succession, to their wives desperately trying to keep up and copy them down.
An oddly English hobby. I don't think there's anything like it over here in the U.S.