It was built in 1940, as one of sixteen pillboxes alongside the Stroudwater Navigation, a canal that links Stroud to the Severn Estuary. It has an octagonal floorplan based on the Type 24 pillbox, the ground floor being constructed of reinforced concrete and the upper storey is red brick. It is situated on the north side of the canal, across from the former Bond's Mill, which was being used during the war by Sperry as a dispersal factory to manufacture gyroscopic compasses. After the war it was adapted for use as a gatehouse for the mill and later to include hydraulic controls for the bridge that crosses the canal.
The historic swing bridge had survived the closure of the navigation in 1954, but had been widened and was no longer operable - it was in a very poor structural condition by the early 1990s.[3] In 1994 the original bridge was replaced with the world's first composite plastic lift bridge for vehicular traffic,[1][4][5] with the weight savings enabling reuse of the original abutments and no requirement for a counterweight.[3]