PILLBOX (TYPE FW3/25)

UF Armco Pillbox
SN A circular pillbox designed by the Engineering and Metals Company using 'Armco' corrugated iron sheets as the inner and outer skins into which concrete was poured, giving a 12in wall thickness. The design was taken up by DFW and assigned a drawing number.
CL MILITARY DEFENCE AND FORTIFICATION
BT PILLBOX