Pillbox construction for Britain’s anti-invasion defences seems to have been organised independently of the pillboxes constructed on the Western Front by the Expeditionary Force, where pillboxes were of much more substantial designs and construction. Perhaps simple and cheap designs capable of rapid construction were more important factors for Home defence. Also pillboxes used for Home Defence would only likely have to face small arms fire and not the heavy shelling on the Western Front. The only overlap seems to have been the Moir Pillbox, of which an allocation was also made for Home Defence although none are known to have erected in Britain.
Three basic types of pillboxwere constructed in Suffolk (circular, hexagonal and square)
Circular Pillbox, cast concrete
This was constructed from cast concrete with a slightly overhanging roof. The embrasures were wide and sometimes at varied levels. The walls were 1’ thick mass concrete and the roof 6” thick, reinforced with 3” RSJ’s. The pillbox was constructed on a 1’ thick concrete raft. Steel doors were provided for the entrance. These were probably the earliest constructed pillboxes and were generally of poor quality. Obvious use had been made of shingle for aggregate, with little attempt at grading. The RSJ’s used to reinforce the roof produced obvious week points. The layout of embrasures varies for each pillbox, presumably to meet the tactical role of the pillbox. These were probably some of the first pillboxes constructed in Britain in 1917.
Above: One of two circular pillboxes, Alderton. Note the varied height of loopholes.
Above: Plan and profile of the second pillbox at Alderton. Note different layout of loopholes.
Above: One of two pillboxes at Shingle Street. Note the two forward loopholes are close together, ensuring maximum fire delivered to the
approach of the bridge it covered. It has been incorporated into the WW2 defences with the addition of Turnbull mounts for LMG's and has
a buttress added for support. Note the entrance seems to be a seperate pre-cast piece.
Above: Left and middle - Pillbox at East Lane. Note the RSJ's used in the construction of the roof create a weak point in the concrete (middle image).
Right image shows another pillbox at Bawdsey which has now been lost to coastal erosion. Note the additional concrete slab added during WW2 to
strengthen the roof.