Visited with kid_in_a_toy_shop on the way back from Nettleton mine. Four substantial gun emplacements and one control bunker/ammunition store (?) dating back to WW2, near Keelby, North Lincs. I guess it was to protect Immingham docks?
All 4 were much the same only more or less overgrown.
All 4 were much the same only more or less overgrown.