Noah
Well-Known Forumite
http://www.pillbox-study-group.org.uk/
There was also the Defence of Britain Project about 20 years ago which mapped & recorded many WWII defences structures, but also missed quite a few. I am sure a report was produced but can't find it. Also -
https://archaeologydataservice.ac.uk/archives/view/dob/ (has a search facility for sites recorded). Or for a little light reading try https://www.amazon.co.uk/Defending-Britain-Twentieth-Century-Structures-Landscape/dp/075243134X
There was also the Defence of Britain Project about 20 years ago which mapped & recorded many WWII defences structures, but also missed quite a few. I am sure a report was produced but can't find it. Also -
https://archaeologydataservice.ac.uk/archives/view/dob/ (has a search facility for sites recorded). Or for a little light reading try https://www.amazon.co.uk/Defending-Britain-Twentieth-Century-Structures-Landscape/dp/075243134X