'Technically speaking' you are talking out of your rectum! . Most of these are pillboxes on the Red Line in Oxfordshire and having visited most of them, been involved in the Pillbox Study Group for many years and researched them extensively at Kew they are generally referred to as pillboxes and not blockhouses. Furthermore most are built to standard designs from rhe FW Dept.
Why the name Pillbox? | The Pillbox Study Group Website. A lot are posted here please add as many as you can United Kingdom
I'm quite surprised that people haven't moved in en-mass. Are there any actual live-in "conversions" anyone is aware of ? Quite a number of the houses on cross-roads etc. look to have been modified too as potential places for defence / over-watch of approaches etc.
Three excellent resources to explore: Defence of Britain Archive Archaeology Data Service Heritage Gateway