Just for fun: the most boring grid square on current OS maps https://www.geograph.org.uk/photo/81429 https://www.geograph.org.uk/photo/81429 Definitely a black

Just for fun: the most boring grid square on current OS maps https://www.geograph.org.uk/photo/81429 https://www.geograph.org.uk/photo/81429 Definitely a black ops site, and don't let the photo convince you otherwise. More seriously, as soon as satellite imagery or even to a lesser extent aerial photography or agents driving around with cameras were a thing, putting the secure site in with a really boring symbol like a landfill site or description like Ind Est would have been a much better disguise.