About 28,000 pillboxes and similar fortifications were built in England in 1940 in preparation for an anticipated invasion. About 6,500 remain; one of them in Beachamwell, north of Walters Cottages (Map Ref TF 7444 0660). A good view can be had walking along Long Drove, aka Searchlight Drove.
It is a standard type 22 pillbox, built using brick shuttering and concrete, and part of the perimeter defence of the Royal Air Force airfield at Marham. The neighbouring parish of Barton Bendish has two similar pillboxes, quite close together, and presumably also part of the Marham airfield defences. The hexagonal structures has loopholes for use by riflemen in five of the walls, and a door in the sixth wall , in this case with small loopholes on each side of the doorway.
The Norfolk Heritage Explorer lists the pillbox here . Mistakenly they describe it as octagonal. However they do point out that the 1946 RAF aerial survey shows the pillbox as part of an almost destroyed complex of small circular structures, probably a searchlight battery, with associated huts. The photograph in question can be seen on the Norfolk Historic Maps website.
According to a document in the Norfolk Record Office in 1949 Norfolk County Council Planning Department considered the future of the pillbox and recommended that “this defence work be place in Category ‘B’ on amenity grounds”. It is not known what this signifies but the pillbox is still standing.
The Pillbox Study Group website has just about everything you would ever want to know about pillboxes and associated anti-invasion defences.