In the late 1930s and early 1940s the German air force carried our aerial reconnaissance of British defences. They identified a number of sites of possible military nature and depicted them on a 1940 map. The map was at 1:50,000 scale, however, and reflects the uncertain nature of the Germans' information. The map included a pillbox identified on a 1940 Luftwaffe reconnnaisance map. Not visible on 1946 aerials