Spotting was something new to me when I came to live in theUK, having never observed it in the USA. After a few months in the UK I came to a conclusion about spotters (that may be born out by Heathrow's comments)
Knowing how important WWII was to the brits, I came to the conclusion that the spottrs were still on the payroll since world war II and that the government simply forgot to take them off the rosters.
At the same time I realized that when they took down the road signs or moved them around to confuse the german invasion force, that they simply never put them back up.
Cheers
Wino